Question

I need help putting this in corresponding factored form. I got two wrong but I’m not sure how to do it and show my work.

Answer 1

Answer:

x^2-16 goes with (x+4)(x-4)

x^2+10x+16 goes with (x+8)(x+2)

Step-by-step explanation:

The first one you got wrong is known as a difference of squares.

To factor a difference of squares, a^2-b^2, you just write it as (a-b)(a+b) or (a+b)(a-b) would work too.

So x^2-16=(x-4)(x+4) or (x+4)(x-4).

Let's check (x+4)(x-4) using foil!

First: x(x)=x^2

Outer: x(-4)=-4x

Inner: 4(x)=4x

Last: 4(-4)=-16

----------------------Add

x^2-16

Bingo! (x+4)(x-4) definitely corresponds to x^2-16.

Here are more examples of factoring a difference of squares:

Example 1:  x^2-25  = (x+5)(x-5)

Example 2: x^2-81   = (x+9)(x-9)

Example 3: x^2-100 =(x+10)(x-10)

Onward to the next problem:

x^2+10x+16

When the coefficient of the leading term of a quadratic is 1, all you have to do is find two numbers that multiply to be c=16 and add up be b=10.

Those numbers would be 8 and 2

because 8(2)=16 and 8+2=10.

So the factored form of x^2+10x+16 is (x+2)(x+8) or (x+8)(x+2).

Here is another example of when the leading coefficient of a quadratic is 1:

Example 1:  x^2+5x+6=(x+2)(x+3) since 3(2)=6 and 3+2=5.

Example 2: x^2-x-6=(x-3)(x+2) since -3(2)=-6 and -3+2=-1.