High School Math : High School Math

Study concepts, example questions & explanations for High School Math

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Example Questions

Example Question #1331 : High School Math

\displaystyle y=\frac{x-3}{x^2-12}

What are the y-intercepts of this equation?

Possible Answers:

\displaystyle y=4

\displaystyle y=\frac{1}{4}

\displaystyle y=0

\displaystyle y=2\sqrt{3}

There are no y-intercepts.

Correct answer:

\displaystyle y=\frac{1}{4}

Explanation:

To find the y-intercept, set \displaystyle x=0 and solve.

\displaystyle y=\frac{x-3}{x^2-12}

\displaystyle y=\frac{(0)-3}{(0)^2-12}

\displaystyle y=\frac{-3}{-12}

\displaystyle y=\frac{1}{4}

Example Question #123 : Mathematical Relationships And Basic Graphs

\displaystyle y=\frac{x^2-64}{x+2}

What are the y-intercepts of this equation?

Possible Answers:

There are no y-intercepts for the equation.

\displaystyle y=-2

\displaystyle y=-32

\displaystyle y=0

\displaystyle y=32

Correct answer:

\displaystyle y=-32

Explanation:

To find the y-intercept, set \displaystyle x=0 and solve.

\displaystyle y=\frac{x^2-64}{x+2}

\displaystyle y=\frac{(0)^2-64}{0+2}

\displaystyle y=\frac{-64}{2}

\displaystyle y=-32

Example Question #131 : Mathematical Relationships And Basic Graphs

\displaystyle y=\frac{3x^2-5}{2x^2+7}

What are the x-intercepts of the equation?

Possible Answers:

\displaystyle x=\sqrt{\frac{5}{3}}, -\sqrt{\frac{5}{3}}

\displaystyle x=0

\displaystyle x=\sqrt{\frac{5}{3}}

\displaystyle x=1

There are no horizontal asymptotes.

Correct answer:

\displaystyle x=\sqrt{\frac{5}{3}}, -\sqrt{\frac{5}{3}}

Explanation:

To find the x-intercepts, we set the numerator equal to zero and solve.

\displaystyle 0=3x^2-5

\displaystyle 5=3x^2

\displaystyle \frac{5}{3}=x^2

\displaystyle \sqrt{\frac{5}{3}}=\sqrt{x^2}

\displaystyle \sqrt{\frac{5}{3}}=x

However, the square root of a number can be both positive and negative.

Therefore the roots will be \displaystyle x=\sqrt{\frac{5}{3}}, -\sqrt{\frac{5}{3}}.

Example Question #132 : Mathematical Relationships And Basic Graphs

\displaystyle y=\frac{x^2-64}{x+2}

What are the x-intercepts of the equation?

Possible Answers:

There are no x-intercepts.

\displaystyle x=0

\displaystyle x=8, -8

\displaystyle x=-2

There are no real x-intercepts.

Correct answer:

\displaystyle x=8, -8

Explanation:

To find the x-intercepts, set the numerator equal to zero.

\displaystyle 0=x^2-64

\displaystyle 64=x^2

\displaystyle \sqrt{64}=\sqrt{x^2}

\displaystyle 8,-8=x

Example Question #3 : Solving Exponential Functions

Solve the equation for \displaystyle x.

\displaystyle \small 9^x=3^6

Possible Answers:

\displaystyle \small x=1

\displaystyle \small x=2

\displaystyle \small x=0

\displaystyle \small x=3

Correct answer:

\displaystyle \small x=3

Explanation:

Begin by recognizing that both sides of the equation have a root term of \displaystyle 3.

\displaystyle \small 9^x=3^6

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

Using the power rule, we can set the exponents equal to each other.

\displaystyle 3^{(2*x)}=3^6

\displaystyle \small 2x=6

\displaystyle \small x=3

Example Question #141 : Algebra Ii

The population of a certain bacteria increases exponentially according to the following equation:

\displaystyle P(t)=2000e^{^{2t}}

where P represents the total population and t represents time in minutes.

How many minutes does it take for the bacteria's population to reach 48,000?

Possible Answers:

\displaystyle \frac{\log 24}{2}

\displaystyle \frac{2}{\ln 24}

\displaystyle \frac{\ln24}{2}

\displaystyle \ln 12

\displaystyle \frac{2}{\log 24}

Correct answer:

\displaystyle \frac{\ln24}{2}

Explanation:

The question gives us P (48,000) and asks us to find t (time). We can substitute for P and start to solve for t:

\displaystyle 48,000 = 2000e^{2t}

\displaystyle 24 = e^{2t}

Now we have to isolate t by taking the natural log of both sides:

\displaystyle \ln 24 = \ln e^{2t}

\displaystyle \ln 24 = (2t)\ln e

And since \displaystyle \ln e = 1, t can easily be isolated:

\displaystyle \ln 24 = 2t

\displaystyle \frac{\ln24}{2} = t

Note: \displaystyle \frac{\ln 24}{2} does not equal \displaystyle \ln 12 . You have to perform the log operation first before dividing.

Example Question #2 : Solving And Graphing Exponential Equations

Solve the equation for \displaystyle x.

\displaystyle \small 3^{2x}=81

Possible Answers:

\displaystyle x=3

\displaystyle x=9

\displaystyle x=1

 

 

 

\displaystyle x=2

 

\displaystyle x=4

Correct answer:

\displaystyle x=2

 

Explanation:

Begin by recognizing that both sides of the equation have the same root term, \displaystyle 3.

\displaystyle \small 3^{2x}=81

\displaystyle \small 3^{2x}=9^2

\displaystyle 3^{2x}=(3^2)^2

We can use the power rule to combine exponents.

\displaystyle 3^{2x}=3^4

Set the exponents equal to each other.

\displaystyle 2x=4

\displaystyle \small x=2

Example Question #32 : Solving And Graphing Exponential Equations

Solve for \displaystyle x:

\displaystyle x^3 - 9x =0

Possible Answers:

\displaystyle x = \{-3,3\}

\displaystyle x = 3

\displaystyle x = \frac{1}{3}

\displaystyle x = 0

\displaystyle x = \{-3,0,3\}

Correct answer:

\displaystyle x = \{-3,0,3\}

Explanation:

Pull an \displaystyle x out of the left side of the equation.

\displaystyle \rightarrow x(x^2 - 9) =0

Use the difference of squares technique to factor the expression in parentheses.

\displaystyle \rightarrow x(x+3)(x-3) =0

Any number that causes one of the terms \displaystyle x\displaystyle x+3, or \displaystyle x-3 to equal \displaystyle 0 is a solution to the equation. These are \displaystyle 0\displaystyle -3, and \displaystyle 3, respectively.

Example Question #1 : Graphing Exponential Functions

Find the \displaystyle y-intercept(s) of \displaystyle y=\frac{x^3+2x+8}{x^2-36}.

Possible Answers:

\displaystyle y=8

\displaystyle y=6

\displaystyle y=\frac{2}{9}

This function does not cross the \displaystyle y-axis.

\displaystyle y=-\frac{2}{9}

Correct answer:

\displaystyle y=-\frac{2}{9}

Explanation:

To find the \displaystyle y-intercept, set \displaystyle x=0 in the equation and solve.

\displaystyle y=\frac{x^3+2x+8}{x^2-36}

\displaystyle y=\frac{(0)^3+2(0)+8}{(0)^2-36}

\displaystyle y=\frac{(0)+(0)+8}{(0)-36}

\displaystyle y=\frac{8}{-36}

\displaystyle y=-\frac{2}{9}

Example Question #141 : Algebra Ii

Find the \displaystyle y-intercept(s) of \displaystyle y=\frac{x^2+9x+8}{x^2-44}.

Possible Answers:

\displaystyle y=-1 and \displaystyle y=-8

\displaystyle y=-\frac{2}{11}

\displaystyle y=\frac{2}{11}

\displaystyle y=2\sqrt{11}

Correct answer:

\displaystyle y=-\frac{2}{11}

Explanation:

To find the \displaystyle y-intercept(s) of \displaystyle y=\frac{x^2+9x+8}{x^2-44}, set the \displaystyle x value equal to zero and solve.

\displaystyle y=\frac{x^2+9x+8}{x^2-44}

\displaystyle y=\frac{(0)^2+9(0)+8}{(0)^2-44}

\displaystyle y=\frac{(0)+(0)+8}{(0)-44}

\displaystyle y=\frac{8}{-44}

\displaystyle y=-\frac{2}{11}

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