Question

16x^2 - 49 when factored is ?

Answer 1

Answer:

(4x-7)(4x+7)

Step-by-step explanation:

This is called the Difference of Two Squares (DOTS).

These are the conditions that must be met for DOTS to work:

•There must be 2 terms.

•They must be separated by a negative sign.

•Each term must be a perfect square.

First, you have to find 2 square numbers that times together to make 16.

4×4=16

As we want 16x², you just need to make the 4 become 4x:

4x times 4x equals 16x²

Then, find 2 squares that times together to make 49.

7×7=49

You can put the two squares into a bracket with the x variable first, then the number:

(4x-7)(4x+7)

In the brackets, you always put the negative sign in the first one and then the plus sign in the second one.

You can double check your answer by expanding it back out again using FOIL:

F-First

O-Outer

I-Inner

L-Last

Times the First two in the two brackets:

4x times 4x equals 16x²

Times the Outer two:

4x times 7 equals 28x

Times the Inner two:

-7 times 4x equals -28x

Times the Last two:

-7 times 7 equals -49

Form an equation:

16x²+28x-28x-49

The 28x cancel out to leave:

16x²-49

Hope this helps :)