Question

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

Answer 1

Answer:

28

Step-by-step 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

Answer 2

Answer:

28.

Step-by-step explanation:

Put r =- 3 and work it out:

That would be 4(3)^2 - 8

=  4 * 9 - 8

= 36 - 8

= 28.