ACT Math : ACT Math

Study concepts, example questions & explanations for ACT Math

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Example Questions

Example Question #12 : Foil

Expand using FOIL:

\(\displaystyle (5m+2)^2\)

Possible Answers:

\(\displaystyle 25m^2+20m+4\)

\(\displaystyle 25m^2+4\)

\(\displaystyle 10m^2+20m+4\)

\(\displaystyle 10m^2+4\)

\(\displaystyle 10m^2+10m+4\)

Correct answer:

\(\displaystyle 25m^2+20m+4\)

Explanation:

Step One: Expand

\(\displaystyle (5m+2)^2=(5m+2)(5m+2)\)

Step 2: Use the FOIL method

First: \(\displaystyle 5m\cdot 5m=25m^2\)

Outside: \(\displaystyle 5m\cdot 2=10m\)

Inside: \(\displaystyle 5m\cdot 2=10m\)

Last: \(\displaystyle 2\cdot 2=4\)

Sum the products:

\(\displaystyle 25m^2+10m+10m+4\)

\(\displaystyle 25m^2+20m+4\)

Example Question #12 : Foil

Use the FOIL method to find the product. The answer must be in standard form.

\(\displaystyle (x^3+2x)(x^6+9x^2)\)

Possible Answers:

\(\displaystyle x^{18}+11x^6+18x^2\)

\(\displaystyle 18x^2+11x^6+x^{18}\)

\(\displaystyle x^9+2x^7+9x^5+18x^3\)

\(\displaystyle 9x^5+2x^7\)

\(\displaystyle 18x^3+9x^5+2x^7+x^9\)

Correct answer:

\(\displaystyle x^9+2x^7+9x^5+18x^3\)

Explanation:

Use the FOIL method to find the product.  The answer must be in standard form.

\(\displaystyle (x^3+2x)(x^6+9x^2)\)

Step 1: Use the FOIL method

First: \(\displaystyle x^3\cdot x^6=x^9\)

Outside: \(\displaystyle x^3\cdot9x^2=9x^5\)

Inside: \(\displaystyle 2x\cdot x^6=2x^7\)

Last: \(\displaystyle 2x \cdot 9x^2=18x^3\)

Add these to find the product:

\(\displaystyle x^9+9x^5+2x^7+18x^3\)

Step 2: Write the product in standard form

Standard form means the terms are written from highest degree to lowest degree. You find the degree of a term by adding the exponents in the term.

Therefore:

\(\displaystyle x^9+2x^7+9x^5+18x^3\)

Example Question #13 : Foil

Simplify:

\(\displaystyle (4r^2+2s^3)^2\)

Possible Answers:

\(\displaystyle 16r^4+12s^3r^2+4s^6\)

\(\displaystyle 4r^4+2s^5\)

\(\displaystyle 16r^4+4s^6\)

\(\displaystyle 16r^4+16s^3r^2+4s^6\)

\(\displaystyle 16r^4+8s^3r^2+4s^6\)

Correct answer:

\(\displaystyle 16r^4+16s^3r^2+4s^6\)

Explanation:

Simplify:

\(\displaystyle (4r^2+2s^3)^2\)

Expand the equation and use the FOIL method:

\(\displaystyle (4r^2+2s^3)(4r^2+2s^3)\)

First: \(\displaystyle 4r^2*4r^2=16r^4\)

Outside: \(\displaystyle 4r^2*2s^3=8s^3r^2\)

Inside: \(\displaystyle 2s^3*4r^2=8s^3r^2\)

Last: \(\displaystyle 2s^3*2s^3=4s^6\)

Sum the terms:

\(\displaystyle 16r^4+8s^3r^2+8s^3r^2+4s^6\)

\(\displaystyle 16r^4+16s^3r^2+4s^6\)

Example Question #14 : Foil

Use FOIL to expand out the following product:
\(\displaystyle (x-4)(2x-3)\)

Possible Answers:

\(\displaystyle x^2 -11x +12\)

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

\(\displaystyle -11x\)

\(\displaystyle 2x^2 +12\)

\(\displaystyle 2x^2-11x +12\)

Correct answer:

\(\displaystyle 2x^2-11x +12\)

Explanation:

FOIL stands for First, Inside, Outside, Last. So multiply the first terms together:
\(\displaystyle x*2x = 2x^2\)

The outside terms:

\(\displaystyle x*(-3)=-3x\)

The inside terms:

\(\displaystyle -4*2x = -8x\)

and the last terms:

\(\displaystyle (-4)*(-3)=12\)

Now combine like terms:

\(\displaystyle 2x^2 + -3x + -8x +12 = 2x^2 -11x+12\)

Example Question #16 : Foil

When \(\displaystyle (2x-5)^2\) is written in its \(\displaystyle ax^2 + bx + c\) form, where \(\displaystyle a\), \(\displaystyle b\), and \(\displaystyle c\) are integers, what is \(\displaystyle a+b+c\)?

Possible Answers:

\(\displaystyle 49\)

\(\displaystyle -21\)

\(\displaystyle -9\)

\(\displaystyle 9\)

\(\displaystyle 20\)

Correct answer:

\(\displaystyle 9\)

Explanation:

In order to get the \(\displaystyle ax^2 + bx + c\) form, we must FOIL out \(\displaystyle (2x-5)^2\).

 

FOIL is technique for distributing two binomials. The letters stand for First, Outer, Inner, and Last.

"First" stands for multiply the terms which occur first in each binomial.

"Outer" stands for multiply the outermost terms in the product.

"Inner" stands for multiply the innermost two terms.

"Last" stands for multiply the terms which occur last in each binomial.

Then, we must simplify the like terms, as shown below:

\(\displaystyle (2x-5)(2x-5) = 4x^2 - 10x - 10x +25 = 4x^2 - 20x +25\).

Here, \(\displaystyle a=4\), \(\displaystyle b=-20\), while \(\displaystyle c=25\), so \(\displaystyle (4) +(-20) + (25) = 9\).

Example Question #14 : Foil

What is the product of: \(\displaystyle (x+7)(2x-4)\)

Possible Answers:

\(\displaystyle x^2 + 10x - 28\)

\(\displaystyle 2x^2 +10x+4\)

\(\displaystyle 12x-28\)

\(\displaystyle 2x^2 +10x - 28\)

\(\displaystyle 2x^2+3x-28\)

Correct answer:

\(\displaystyle 2x^2 +10x - 28\)

Explanation:

Use FOIL to multiply the products. 
First terms: \(\displaystyle x*2x=2x^2\)

Outside terms: \(\displaystyle x*(-4)=-4x\)

Inside terms: \(\displaystyle 7*2x = 14x\)

Last terms: \(\displaystyle 7*(-4)=-28\)
Now combine like terms: \(\displaystyle 2x^2-4x+14x -28 = 2x^2+10x-28\)

Example Question #2601 : Act Math

Find the product of the two binomials:
\(\displaystyle (2x-4)(x+8)\)

Possible Answers:

\(\displaystyle 14x-32\)

\(\displaystyle 2x^2 + 12x +4\)

\(\displaystyle -2x^2 + 4x +12\)

\(\displaystyle 2x^2+12x-32\)

\(\displaystyle x^2+14x-32\)

Correct answer:

\(\displaystyle 2x^2+12x-32\)

Explanation:

Use FOIL (First Outside Inside Last) to multiply the binomials:

\(\displaystyle 2x*x = 2x^2\)

\(\displaystyle 2x*8 = 16x\)

\(\displaystyle -4*x = -4x\)

\(\displaystyle -4*8 = -32\)

now combine like terms and you get the result: \(\displaystyle 2x^2+12x-32\)

Example Question #22 : How To Use Foil With The Distributive Property

Expand the following: \(\displaystyle \textup{(x+5)(x+3)}\)

Possible Answers:

\(\displaystyle \textup{8x}\)

\(\displaystyle \textup{x}^{2}+\textup{8x}+15\)

\(\displaystyle \textup{2x}+8\)

\(\displaystyle \textup{x}^{2}+15\)

\(\displaystyle \textup{2x}^{2}+15\)

Correct answer:

\(\displaystyle \textup{x}^{2}+\textup{8x}+15\)

Explanation:

To reach the solution, use the FOIL method of the distributive property. This stands for First, Outer, Inner, Last. In this particular problem, we begin by multiplying the first two \(\displaystyle \textup{x's}\) together, yielding \(\displaystyle {\textup{x}}^{2}\). Then, we multiply \(\displaystyle \textup{x}\) by the outer number, which is \(\displaystyle 3\), yielding \(\displaystyle \textup{3x}\). Next, we multiply the two inner numbers, \(\displaystyle 5\) and \(\displaystyle \textup{x}\), yielding \(\displaystyle \textup{5x}\). Finally, we multiply the last two numbers, \(\displaystyle 5\) and \(\displaystyle 3\), yielding \(\displaystyle 15\). Thus, when we add all those together, the answer is  \(\displaystyle \textup{x}^{2}+\textup{8x}+15\).

Example Question #2601 : Act Math

Distribute: \(\displaystyle (x+2)(x-3)\)

Possible Answers:

\(\displaystyle 2x-6\)

\(\displaystyle x-6\)

\(\displaystyle x^{2}-x-6\)

\(\displaystyle x^2-6\)

Correct answer:

\(\displaystyle x^{2}-x-6\)

Explanation:

To FOIL using the distributive property, multiply the first terms together, then the outer terms, then the inner terms, and finally, the last terms. 

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

Example Question #2602 : Act Math

Distribute: \(\displaystyle (6x-2)^{2}\)

Possible Answers:

\(\displaystyle 12x^2-24x+4\)

\(\displaystyle 36x^2-24x+4\)

\(\displaystyle 36x^2+24x+4\)

\(\displaystyle 36x^2+4\)

Correct answer:

\(\displaystyle 36x^2-24x+4\)

Explanation:

To FOIL using the distributive property, multiply the first terms together, then the outer terms, then the inner terms, and finally, the last terms.

\(\displaystyle (6x-2)^2=36x^2-12x-12x+4=36x^2-24x+4\)

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