High School Math : Intermediate Single-Variable Algebra

Study concepts, example questions & explanations for High School Math

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Example Questions

Example Question #1 : Using Foil

FOIL \displaystyle (x+2)(x-2).

Possible Answers:

\displaystyle x^2-4

\displaystyle x^2+4x+4

\displaystyle x^2-2x+2

\displaystyle x^2+x-2

\displaystyle x^2+4

Correct answer:

\displaystyle x^2-4

Explanation:

Remember FOIL stands for First Outer Inner Last. That means we can take \displaystyle (x+2)(x-2) and turn it into \displaystyle x^2+2x-2x-4.

Simplify to get \displaystyle x^2-4.

Example Question #42 : Intermediate Single Variable Algebra

FOIL \displaystyle (x+5)^2.

Possible Answers:

\displaystyle x^2-10x+25

\displaystyle x^2+10x+25

\displaystyle x^2+25x+25

\displaystyle 5x^2

\displaystyle x^2+25

Correct answer:

\displaystyle x^2+10x+25

Explanation:

\displaystyle (x+5)^2 is the same thing as \displaystyle (x+5)(x+5).

Remember that FOIL stands for First Outer Inner Last.

For this problem, that would be \displaystyle x^2+5x+5x+25

Simplify that to \displaystyle x^2+10x+25.

Example Question #3 : Understanding Quadratic Equations

FOIL \displaystyle (x+5)(x-1).

Possible Answers:

\displaystyle x^2+4x-5

\displaystyle x^2+24

\displaystyle x^2-4x-5

\displaystyle x^2-5

\displaystyle x^2+5x+5

Correct answer:

\displaystyle x^2+4x-5

Explanation:

Remember that FOIL stands for First Outer Inner Last.

For this problem that would give us:

\displaystyle (x+5)(x-1)

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

Simplify.

\displaystyle x^2+4x-5

Example Question #44 : Intermediate Single Variable Algebra

FOIL \displaystyle (x+2)(x-2).

Possible Answers:

\displaystyle x^2-4

\displaystyle x^2+4

\displaystyle x^2-4x-4

\displaystyle x^2-4x

\displaystyle -x^2+4

Correct answer:

\displaystyle x^2-4

Explanation:

Remember that FOIL stands for First Outer Inner Last.

For this problem that would give us:

\displaystyle (x+2)(x-2)

\displaystyle =x^2-2x+2x-4

Simplify:

\displaystyle =x^2-4

 

 

Example Question #1 : Using Foil

Solve the equation for \displaystyle x.

\displaystyle \small \frac{1}{x}=\frac{x+1}{6}

Possible Answers:

\displaystyle \small x=3\ or\ -2

\displaystyle \small x=-3\ or\ 2

\displaystyle \small x=3\ or\ 2

\displaystyle \small x=-3\ or\ -2

Correct answer:

\displaystyle \small x=-3\ or\ 2

Explanation:

\displaystyle \small \small \frac{1}{x}=\frac{x+1}{6}

Cross multiply.

\displaystyle \small 6=x(x+1)

\displaystyle \small 6=x^2+x

Set the equation equal to zero.

\displaystyle \small 0=x^2+x-6

Factor to find the roots of the polynomial.

\displaystyle 3*-2=-6 and \displaystyle 3+(-2)=1

\displaystyle \small 0=(x+3)(x-2)

\displaystyle \small 0=x+3; x=-3

\displaystyle \small 0=x-2; x=2

Example Question #2 : Using Foil

Evaluate \displaystyle (2x+3)^{2}

Possible Answers:

\displaystyle \dpi{100} 4x+12

\displaystyle \dpi{100} 4x^{2}+9x+9

\displaystyle \dpi{100} 4x^{3}+12x^{2}+9x

\displaystyle \dpi{100} \dpi{100} 4x^{2}+9

\displaystyle 4x^{2}+12x+9

Correct answer:

\displaystyle 4x^{2}+12x+9

Explanation:

In order to evaluate \displaystyle (2x+3)^{2} one needs to multiply the expression by itself using the laws of FOIL.  In the foil method, one multiplies in the following order: first terms, outer terms, inner terms, and last terms.

\displaystyle \dpi{100} (2x+3)^{2}=(2x+3)(2x+3)

Multiply terms by way of FOIL method.

\displaystyle =(2x*2x)+(2x*3)+(3*2x)+(3*3)

Now multiply and simplify.

\displaystyle =4x^{2}+6x+6x+9

\displaystyle \rightarrow 4x^{2}+12x+9

Example Question #41 : Intermediate Single Variable Algebra

Expand \displaystyle (x+7)(x-2).

Possible Answers:

\displaystyle x^2+9

\displaystyle x^2+7x-2x-7

\displaystyle x^2-5x-14

\displaystyle x^2+5x-14

\displaystyle x^2-14x+5

Correct answer:

\displaystyle x^2+5x-14

Explanation:

To solve our given equation, we need to use FOIL (First, Outer, Inner, Last).

\displaystyle (x+7)(x-2)=x^2-2x+7x-14

Combine like terms.

\displaystyle (x+7)(x-2)=x^2+5x-14

Example Question #42 : Intermediate Single Variable Algebra

FOIL \displaystyle (x+1)(x-3).

Possible Answers:

\displaystyle x^2-4x-3

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

\displaystyle x^2+3x+4

\displaystyle x^2-2x-3

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

Correct answer:

\displaystyle x^2-2x-3

Explanation:

Remember FOIL stands for First Outer Inner Last.

\displaystyle (x+1)(x-3)=x^2+1x-3x-3

Combine like terms to get \displaystyle x^2-2x-3.

Example Question #293 : Algebra Ii

Use the discriminant to determine the nature of the roots:

\displaystyle 4x^2-40x+25=0

Possible Answers:

\displaystyle 2 irrational roots

\displaystyle 2 rational roots

\displaystyle 2 imaginary roots

\displaystyle 1 imaginary root

\displaystyle 1 rational root

Correct answer:

\displaystyle 2 irrational roots

Explanation:

The formula for the discriminant is:

\displaystyle b^2 - 4ac

\displaystyle =(-40)^2 - 4(4)(25)

\displaystyle =1200^{}

Since the discriminant is positive and not a perfect square, there are \displaystyle 2 irrational roots.

Example Question #12 : Quadratic Equations And Inequalities

Use the discriminant to determine the nature of the roots:

\displaystyle 2y^2+6y+5=0

Possible Answers:

\displaystyle 1 rational root

\displaystyle 1 imaginary root

\displaystyle 2 imaginary roots

\displaystyle 2 irrational roots

\displaystyle 2 rational roots

Correct answer:

\displaystyle 2 imaginary roots

Explanation:

The formula for the discriminant is:

\displaystyle b^2 - 4ac

\displaystyle =(6)^2 - 4(2)(5)

\displaystyle =-4

Since the discriminant is negative, there are \displaystyle 2 imaginary roots.

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