Algebra 1 : How to use FOIL in the distributive property

Study concepts, example questions & explanations for Algebra 1

varsity tutors app store varsity tutors android store

Example Questions

Example Question #161 : How To Use Foil In The Distributive Property

Multiply: \(\displaystyle (x+3y)\)and \(\displaystyle (y^2+3xy+2)\)

Possible Answers:

\(\displaystyle 3y^3 +9xy^2 + 4x^2 y+2x+6y\)

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

\(\displaystyle 3y^3 +9xy^2 + 4x^2 y+6x+2y\)

\(\displaystyle 3y^3 +10xy^2 + 3x^2 y+2x+6y\)

Correct answer:

\(\displaystyle 3y^3 +10xy^2 + 3x^2 y+2x+6y\)

Explanation:

Here we have to use the distributive property and FOIL when we are multiplying the two terms. First we multipy the terms in the binomial with the trinomial. Then we add or subtract the coefficients of the terms with same combination of variables x and y.

\(\displaystyle (x+3y) (y^2+3xy+2)\)

\(\displaystyle = x(y^2+3xy+2) +3y(y^2+3xy+2)\)

\(\displaystyle = xy^2+3x^2y+2x +3y^3+9xy^2+6y\)

\(\displaystyle = 3y^3+10xy^2+3x^2y+2x+6y\)

Example Question #162 : How To Use Foil In The Distributive Property

Multiply:  \(\displaystyle (3x-6)(3-x)\)

Possible Answers:

\(\displaystyle -3x^2-3x+18\)

\(\displaystyle -3x^2-15x+18\)

\(\displaystyle -3x^2+15x-18\)

\(\displaystyle -3x^2-15x-18\)

\(\displaystyle -3x^2+3x-18\)

Correct answer:

\(\displaystyle -3x^2+15x-18\)

Explanation:

Use the FOIL method to multiply the terms.

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

Simplify the terms on the right side of the equation.

\(\displaystyle 9x-3x^2-18+6x\)

Combine like-terms.

The answer is:  \(\displaystyle -3x^2+15x-18\)

Example Question #4971 : Algebra 1

Distribute using FOIL:

\(\displaystyle (4x+3)(2x-6)\)

Possible Answers:

\(\displaystyle 8x^{2}+8x-18\)

\(\displaystyle 6x^{2}+12x-18\)

\(\displaystyle 8x^{2}+18x-12\)

\(\displaystyle 8x-18\)

\(\displaystyle 8x^{2}-18x-18\)

Correct answer:

\(\displaystyle 8x^{2}-18x-18\)

Explanation:

As we know, FOIL stands for First, Outside, Inside, Last, which indicates the order in which we should multiply each of these terms.

First: \(\displaystyle 4x\cdot2x=8x^{2}\)

Outside: \(\displaystyle 4x\cdot-6=-24x\)

Inside: \(\displaystyle 3\cdot2x=6x\)

Last: \(\displaystyle 3\cdot-6=-18\)

We then combine like terms, which in this case are \(\displaystyle -24x\) and \(\displaystyle 6x\). When we add these together, we are left with a trinomial of \(\displaystyle 8x^{2}-18x-18\). None of the remaining terms are alike, so there is no further simplification possible.

Example Question #161 : Distributive Property

Expand:

\(\displaystyle (5-4x)(-3+x)\)

Possible Answers:

\(\displaystyle -4x^2+17x-15\)

\(\displaystyle 4x^2-17x+15\)

\(\displaystyle -4x^2-15\)

\(\displaystyle -4x^2-7x-15\)

\(\displaystyle -4x^2+7x-15\)

Correct answer:

\(\displaystyle -4x^2+17x-15\)

Explanation:

To expand this set of binomials we need to FOIL the terms. FOIL is the multiplication steps that need to be applied to a set of binomials.

\(\displaystyle (5-4x)(-3+x)\)

First:  \(\displaystyle 5\cdot -3=-15\)

Outer:  \(\displaystyle 5\cdot x=5x\)

Inner:\(\displaystyle -4x\cdot-3=12x\)

Last:\(\displaystyle -4x\cdotx=-4x^{2}\)

 

\(\displaystyle $Sum$ =-15+5x+12x-4x^2 = -4x^2+17x-15\)

Example Question #4971 : Algebra 1

Multiply \(\displaystyle (3x+4)(x-2)\)

Possible Answers:

\(\displaystyle 3x^2-8\)

\(\displaystyle 4x+2\)

\(\displaystyle 3x^2+10x+8\)

\(\displaystyle 3x^2 -2x -8\)

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

Correct answer:

\(\displaystyle 3x^2 -2x -8\)

Explanation:

Use the FOIL method to multiply the polynomials:

(3x+4)(x-2)

 

 F - Multiply the first terms of each binomial

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

 

O- Multiply the outside terms of each binomial

\(\displaystyle 3x*-2 = -6x\)

 

I- Multiply the inside terms of each binomial

 \(\displaystyle 4*x=4x\)

 

L- Multiply the last terms of each binomial

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

 

Add all of the answers and combine like terms

\(\displaystyle 3x^2-6x+4x-8\)

\(\displaystyle 3x^2-2x-8\)

Example Question #161 : How To Use Foil In The Distributive Property

Simplify the following expression.

\(\displaystyle (3x-8)(4y+7)\)

Possible Answers:

\(\displaystyle 12x^{2}-11x-56\)

\(\displaystyle 12xy+21x-32y-56\)

\(\displaystyle 12xy+21x+32y+56\)

None of the other answers.

\(\displaystyle 12xy+11xy-56\)

Correct answer:

\(\displaystyle 12xy+21x-32y-56\)

Explanation:

Use FOIL to distribute each term.

F: \(\displaystyle 3x(4y)=12xy\)

O: \(\displaystyle 3x(7)=21x\)

I: \(\displaystyle -8(4y)=-32y\)

L:\(\displaystyle -8(7)=-56\)

If possible, combine like terms (none in this case).

\(\displaystyle 12xy+21x-32y-56\)

Example Question #161 : Distributive Property

Factor the following expression.

\(\displaystyle x^{2}+7x+12\)

Possible Answers:

\(\displaystyle (x+9)(x+3)\)

\(\displaystyle (x+4)(x+3)\)

\(\displaystyle (x+12)(x-5)\)

\(\displaystyle (x+6)(x+2)\)

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

Correct answer:

\(\displaystyle (x+4)(x+3)\)

Explanation:

For an expression in the form \(\displaystyle ax^{2}+bx+c\), in its simplest form where \(\displaystyle a=1\), find two integers whose sum is \(\displaystyle b\) and whose product is \(\displaystyle c\).

 

In the case of

3 and 4 fit the requirements. Therefore, our answer looks like:

Example Question #4981 : Algebra 1

Factor the following expression.

\(\displaystyle x^{2}-2x-63\)

Possible Answers:

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

\(\displaystyle (x-7)(x-9)\)

\(\displaystyle (x+65)(x-2)\)

\(\displaystyle (x-7)(x+9)\)

\(\displaystyle (x+7)(x-9)\)

Correct answer:

\(\displaystyle (x+7)(x-9)\)

Explanation:

For an expression in the form \(\displaystyle ax^{2}+bx+c\), in its simplest form where \(\displaystyle a=1\), find two integers whose sum is \(\displaystyle b\) and whose product is \(\displaystyle c\).

In the case of

\(\displaystyle x^{2}-2x-63\)

\(\displaystyle -9\) and \(\displaystyle 7\) fit the requirements. Therefore, our answer looks like:

Learning Tools by Varsity Tutors