Consider the functions

Question

Find f(5) f(x)=3x²-5

Answer 1

Hi, Alia!

The key here is to substitute 5 into x, and remember the order of operations using PEMDAS:

1. Parentheses
2. Exponents
3. Multiplication and Division
4. Addition and Subtraction

SO, we have

f(x)=3x²-5

Substitute x=5 to get

f(5) = 3·5²-5

There are no Parentheses, so we resolve the Exponent first. 5 squared equals 25.

f(5) = 3·25-5

Next, Multiplication. 3 times 25 equals 75.

f(5) = 75-5

Lastly, since there is no Division, we go to Addition/Subtraction. 75 minus 5 is 70, and that is the final answer.

f(5) = 70.

Hope this helped!