Question

What is the value of 4r^2-8 when r=3?

Answer 1

28.

Explanation:

Put r =- 3 and work it out:

That would be 4(3)^2 - 8

= 4 * 9 - 8

= 36 - 8

= 28.

Answer 2

28

Explanation:

So this means to replace the r you see in 4r^2-8 with 3.

Let's do that:

4(3)^2-8

Now to simplify this just use pemdas or a calculator:

4(9)-8 since 3^2 means 3*3=9

36-8

28