For the function f(x)=3x^2-8x find:
a. f(2)
= -4
b. f(-3)
= 51
Right?
a) 3(2)^2 - 8(2)
= 6^2 - 16
= 36-16
= 20
b) 3(-3)^2-8(-3)
= -9^2 - (-24)
= 81 + 24
= 105
Cyn.. That can't be right. Try it on a calculator..
Watch your order of operation.
a) 3(2)^2 - 8(2)
= 3(4) - 16
= 12 - 16
= -4
Now do b) the same way, the power has to be done first.
Yeah. 51, like I said, right?
Yes, C. , you are right.
I was not paying attention that it was "anonymous" who gave the wrong solution, I thought it was you.
You were right with both answers.
To find the value of a function for a specific value of x, you simply substitute that value into the function and evaluate the expression.
a. To find f(2), substitute x = 2 into the function:
f(2) = 3(2)^2 - 8(2)
= 3(4) - 16
= 12 - 16
= -4
So, f(2) equals -4.
b. Similarly, to find f(-3), substitute x = -3 into the function:
f(-3) = 3(-3)^2 - 8(-3)
= 3(9) + 24
= 27 + 24
= 51
So, f(-3) equals 51.
Therefore, your answers are correct.