AP Calculus AB : Asymptotic and Unbounded Behavior

Study concepts, example questions & explanations for AP Calculus AB

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Example Questions

Example Question #88 : Comparing Relative Magnitudes Of Functions And Their Rates Of Change

\displaystyle \int_3^64x^2+\frac{2}{3}x{\mathrm{d} x}=?

Possible Answers:

\displaystyle 261

\displaystyle 339

\displaystyle 87

\displaystyle 300

\displaystyle 7.69

Correct answer:

\displaystyle 261

Explanation:

To find the definite integral, we can use the Fundamental Theorem of Calculus which states that if \displaystyle g'(x)=f(x), then \displaystyle \int_a^bf(x)=g(b)-g(a).

Therefore, we need to find the indefinite integral of our equation to start.

To find the indefinite integral, we can use the reverse power rule. We raise the exponent of the variable by one and divide by our new exponent.

\displaystyle \int 4x^2+\frac{2}{3}x{\mathrm{d} x}=\frac{4x^{2+1}}{2+1}+\frac{\frac{2}{3}x^{1+1}}{1+1}+c

Remember to include a \displaystyle +c to cover any potential constant that might be in our new equation.

\displaystyle \int 4x^2+\frac{2}{3}x{\mathrm{d} x}=\frac{4x^{3}}{3}+\frac{\frac{2}{3}x^{2}}{2}+c

\displaystyle \int 4x^2+\frac{2}{3}x{\mathrm{d} x}=\frac{4}{3}x^3+\frac{1}{3}x^2+c

Plug that into FTOC:

\displaystyle \int_a^b 4x^2+\frac{2}{3}x{\mathrm{d} x}=(\frac{4}{3}b^3+\frac{1}{3}b^2+c)-(\frac{4}{3}a^3+\frac{1}{3}a^2+c)

Notice that the \displaystyle c's cancel out.

Plug in our given values.

\displaystyle \int_3^6 4x^2+\frac{2}{3}x{\mathrm{d} x}=(\frac{4}{3}(6)^3+\frac{1}{3}(6)^2)-(\frac{4}{3}(3)^3+\frac{1}{3}(3)^2)

\displaystyle \int_3^6 4x^2+\frac{2}{3}x{\mathrm{d} x}=(\frac{4}{3}(216)+\frac{1}{3}(36))-(\frac{4}{3}(27)+\frac{1}{3}(9))

\displaystyle \int_3^6 4x^2+\frac{2}{3}x{\mathrm{d} x}=(288+12)-(36+3)

\displaystyle \int_3^6 4x^2+\frac{2}{3}x{\mathrm{d} x}=(300)-(39)

\displaystyle \int_3^6 4x^2+\frac{2}{3}x{\mathrm{d} x}=261

Example Question #89 : Comparing Relative Magnitudes Of Functions And Their Rates Of Change

\displaystyle \int_{-\pi}^{\pi}\sin(x){\mathrm{d} x}=?

Possible Answers:

\displaystyle 1

\displaystyle -2

\displaystyle 2\pi

\displaystyle 1

\displaystyle 0

Correct answer:

\displaystyle 0

Explanation:

The fundamental theorem of calculus states that if \displaystyle f'(x)=g(x), then \displaystyle \int_a^bg(x){\mathrm{d} x}=f(b)-f(a).

First, we need to find the indefinite integral of our given equation. Just like with the derivatives, the indefinite integrals or anti-derivatives of trig functions must be memorized.

\displaystyle \int \sin(x){\mathrm{d} x}=-\cos(x)+c

Don't forget the \displaystyle +c to compensate for any potential constant!

Plug this in to our FTOC:

\displaystyle \int_b^a \sin(x){\mathrm{d} x}=(-\cos(b)+c)-(-\cos(a)+c).

Notice that the \displaystyle +c's cancel out.

\displaystyle \int_b^a \sin(x){\mathrm{d} x}=-\cos(b)+\cos(a).

Now plug in the given values.

\displaystyle \int_{-\pi}^{\pi} \sin(x){\mathrm{d} x}=-\cos(\pi)+\cos(-\pi)

\displaystyle \int_{-\pi}^{\pi} \sin(x){\mathrm{d} x}=0+0

\displaystyle \int_{-\pi}^{\pi} \sin(x){\mathrm{d} x}=0

Example Question #90 : Comparing Relative Magnitudes Of Functions And Their Rates Of Change

\displaystyle \int_2^8 4x^2+5x-3\: dx=?

Possible Answers:

\displaystyle 216

\displaystyle 804

\displaystyle 270

\displaystyle 810

Correct answer:

\displaystyle 804

Explanation:

To solve for the definite integral, use the fundamental theorem of calculus. If \displaystyle g'(x)=f(x), then \displaystyle \int_a^bf(x)=g(b)-g(a).

First we need to find the indefinite integral.

To find the indefinite integral of our given equation, we can use the reverse power rule: we raise the exponent by one and then divide by that new exponent.

\displaystyle \int 4x^2+5x-3\: dx=\frac{4x^{2+1}}{2+1}+\frac{5x^{1+1}}{1+1}-\frac{3x^{0+1}}{0+1}+c

Don't forget to include a \displaystyle +c to compensate for any constant!

\displaystyle \int 4x^2+5x-3\: dx=\frac{4x^{3}}{3}+\frac{5x^{2}}{2}-\frac{3x^{1}}{1}+c

\displaystyle \int 4x^2+5x-3\: dx=\frac{4}{3}x^3+\frac{5}{2}x^2-3x+c

Plug this into our first FTOC equation:

\displaystyle \int_a^b 4x^2+5x-3\: dx=(\frac{4}{3}b^3+\frac{5}{2}b^2-3b+c)-(\frac{4}{3}a^3+\frac{5}{2}a^2-3a+c)

Notice that the \displaystyle c's cancel out.

\displaystyle \int_a^b 4x^2+5x-3\: dx=(\frac{4}{3}b^3+\frac{5}{2}b^2-3b)-(\frac{4}{3}a^3+\frac{5}{2}a^2-3a)

Plug in our given values.

\displaystyle \int_2^8 4x^2+5x-3\: dx=(\frac{4}{3}(8)^3+\frac{5}{2}(8)^2-3(8))-(\frac{4}{3}(2)^3+\frac{5}{2}(2)^2-3(2))

\displaystyle \int_2^8 4x^2+5x-3\: dx=804

Example Question #113 : Functions, Graphs, And Limits

Find the indefinite ingtegral for \displaystyle \int\frac{x+1}{\sqrt{x}} dx.

Possible Answers:

\displaystyle x^{}\frac{3}{2}+ x^{\frac{1}{2}}+C

\displaystyle \frac{2}{3}x^{\frac{3}{2}}+2x^{\frac{1}{2}}+C

\displaystyle (x-2)^\frac{3}{2}

Correct answer:

\displaystyle \frac{2}{3}x^{\frac{3}{2}}+2x^{\frac{1}{2}}+C

Explanation:

First, bring up the radical into the numerator and distribute to the (x+1) term.

\displaystyle (x+1)x^{\frac{-1}{2}}

\displaystyle \int x^{\frac{1}{2}} + x^{\frac{-1}{2}}dx

Then integrate.

\displaystyle \frac{2}{3}x^{\frac{3}{2}}+ 2x^{\frac{1}{2}}

 

Since it's indefinite, don't forget to add the C: 

\displaystyle \frac{2}{3}x^{\frac{3}{2}}+ 2x^{\frac{1}{2}}+C

 

 

Example Question #111 : Asymptotic And Unbounded Behavior

Integrate this function: \displaystyle \int(x+6)dx

Possible Answers:

\displaystyle x^2 + 6x+C

\displaystyle \frac{x^2}{2}+6x+C

\displaystyle x^2+6x

Correct answer:

\displaystyle \frac{x^2}{2}+6x+C

Explanation:

First, divide up into two different integral expressions:

\displaystyle \int xdx + \int6dx

Then, integrate each: 

\displaystyle \frac{x^2}{2} + 6x

Don't forget "C" because it is an indefinite integral:

\displaystyle \frac{x^2}{2} + 6x+C

 

Example Question #121 : Functions, Graphs, And Limits

Integrate the following expression: \displaystyle \int(2x^4-6x^3+9x)dx

Possible Answers:

\displaystyle \frac{2x^5}{5}-\frac{3x^4}{2}+\frac{9x^2}{2}+C

\displaystyle 2x^5-3x^4+9x^2

\displaystyle x^5-x^4+x^2+C

Correct answer:

\displaystyle \frac{2x^5}{5}-\frac{3x^4}{2}+\frac{9x^2}{2}+C

Explanation:

First, divide up into three different expressions so you can integrate each x term separately:

\displaystyle \int2x^{4}dx-\int6x^{3}dx+\int9xdx

Then, integrate and simplify:

\displaystyle 2(\frac{x^{5}}{5})-6(\frac{x^4}{4})+9(\frac{x^2}{2})

\displaystyle \frac{2x^5}{5}-\frac{3x^4}{2}+\frac{9x^2}{2}

 

Don't forget "C" because it's an indefinite integral: 

\displaystyle \frac{2x^5}{5}-\frac{3x^4}{2}+\frac{9x^2}{2}+C

Example Question #122 : Functions, Graphs, And Limits

Find the general solution of \displaystyle \int\frac{1}{x^3}dx to find the particular solution that satisfies the intitial condition F(1)=0

Possible Answers:

\displaystyle F(x)=-\frac{1}{2x^2}+\frac{1}{2}

\displaystyle F(x)=-2x^2+\frac{1}{2}

\displaystyle F(x)=\frac{1}{2x^2}+\frac{1}{2}

Correct answer:

\displaystyle F(x)=-\frac{1}{2x^2}+\frac{1}{2}

Explanation:

To start the problem, it's easier if you bring up the denominator and make it a negative exponent:

\displaystyle \int x^{-3}dx

Then, integrate:

\displaystyle \frac{x^{-2}}{-2}

Simplify and add the "C" for an indefinite integral:


\displaystyle -\frac{1}{2x^2}+ C

Plug in the initial conditions [F(1)=0] to find C and generate the particular solution:

\displaystyle -\frac{1}{2x^2}+C=0

\displaystyle -\frac{1}{2(1^2)}+C=0

\displaystyle C=\frac{1}{2}

Thus, your final equation is: 

\displaystyle F(x)=-\frac{1}{2x^2}+\frac{1}{2}

 

Example Question #123 : Functions, Graphs, And Limits

Integrate: 

\displaystyle \int(2x-3x^2)dx

Possible Answers:

\displaystyle -x^3+x^2 +C

\displaystyle 4x^2-\frac{9}{2}x^3+C

\displaystyle \frac{4}{3}x^3+\frac{9}{2}x^2+C

\displaystyle x^3-x^2+C

Correct answer:

\displaystyle -x^3+x^2 +C

Explanation:

First, split up into 2 integrals:

\displaystyle \int2xdx-\int3x^2dx

Then integrate and simplify:

\displaystyle 2(\frac{x^2}{2})-3(\frac{x^3}{3})

\displaystyle x^2-x^3

Don't forget to add C because it's an indefinite integral:

\displaystyle -x^3+x^2 +C

Example Question #124 : Functions, Graphs, And Limits

Integrate: 

\displaystyle \int(x^3+2)^2dx

Possible Answers:

\displaystyle x^7+x^4+4x+C

\displaystyle \frac{x^7}{7}+x^4+4x+C

\displaystyle \frac{x^7}{7}-x^4+4x+C

\displaystyle 7x^7+x^4+4x+C

Correct answer:

\displaystyle \frac{x^7}{7}+x^4+4x+C

Explanation:

First, FOIL the binomial:

\displaystyle (x^3+2)(x^3+2)= x^6+4x^3+4

Once that's expanded, integrate each piece separately:

\displaystyle \int x^6dx+\int4x^3dx+\int4dx

\displaystyle \frac{x^7}{7}+4(\frac{x^4}{4})+4x

Then simplify and add C because it's an indefinite integral:

\displaystyle \frac{x^7}{7}+x^4+4x+C

 

Example Question #112 : Asymptotic And Unbounded Behavior

\displaystyle \int^6_3 x^2+5x\ dx =

Possible Answers:

\displaystyle 27

\displaystyle 193.5

\displaystyle 130.5

Undefined

\displaystyle 31.5

Correct answer:

\displaystyle 130.5

Explanation:

Remember the Rundamental Theorem of Calculus: If \displaystyle g'(x)=f(x), then \displaystyle \int^b_af(x){\mathrm{d} x}=g(b)-g(a).

To solve for the indefinite integral, we can use the reverse power rule. We raise the power of the exponents by one and divide by that new exponent. For this problem, that would look like:

\displaystyle \int x^2+5x{\mathrm{d} x}=\frac{x^{2+1}}{2+1}+\frac{5x^{1+1}}{1+1}+c

Remember, when taking an integral, definite or indefinite, we always add \displaystyle +c, as there could be a constant involved.

\displaystyle \int x^2+5x{\mathrm{d} x}=\frac{1}{3}x^3+\frac{5}{2}x^2+c

Now we can plug that back into the problem.

\displaystyle \int^b_a x^2+5x{\mathrm{d} x}=(\frac{1}{3}b^3+\frac{5}{2}b^2+c)-(\frac{1}{3}a^3+\frac{5}{2}a^2+c)

Notice that the \displaystyle c's cancel out. Plug in the values given in the problem:

\displaystyle \int^6_3 x^2+5x{\mathrm{d} x}=(\frac{1}{3}(6)^3+\frac{5}{2}(6)^2)-(\frac{1}{3}(3)^3+\frac{5}{2}(3)^2)\displaystyle \int^6_3 x^2+5x{\mathrm{d} x}=(\frac{1}{3}*216+\frac{5}{2}*36)-(\frac{1}{3}*27+\frac{5}{2}*9)

\displaystyle \int^6_3 x^2+5x{\mathrm{d} x}=(72+90)-(9+22.5)

\displaystyle \int^6_3 x^2+5x{\mathrm{d} x}=(162)-(31.5)

\displaystyle \int^6_3 x^2+5x{\mathrm{d} x}=130.5

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