SOLUTION: If f(x) = 3x^2 - Bx + 4, and f(-1) = 12, what is the value of B? Let me give it a try. Let x = -1 and f(-1) be 12. 3(-1)^2 - B(-1) + 4 12 = 3(-1)^2 -B(-1) + 4

Algebra ->  Functions -> SOLUTION: If f(x) = 3x^2 - Bx + 4, and f(-1) = 12, what is the value of B? Let me give it a try. Let x = -1 and f(-1) be 12. 3(-1)^2 - B(-1) + 4 12 = 3(-1)^2 -B(-1) + 4       Log On


   

Question 1208026: If f(x) = 3x^2 - Bx + 4, and f(-1) = 12, what is the value of B?

Let me give it a try.

Let x = -1 and f(-1) be 12.

3(-1)^2 - B(-1) + 4

12 = 3(-1)^2 -B(-1) + 4

12 = 3(1) + B + 4

12 = 3 + B + 4

12 = B + 7

12 - 7 = B

5 = B

You say?


Found 2 solutions by josgarithmetic, ikleyn:
Answer by josgarithmetic(39617) About Me  (Show Source):
You can put this solution on YOUR website!
f%28-1%29=12 means that the point (-1,12) is a point on the function f.

Use that known point for x and f(x).
12=3%28-1%29%5E2-B%28-1%29%2B4
3%2BB%2B4=12
B%2B7=12
highlight%28B=5%29----------and could have been done in one or two fewer steps.

Answer by ikleyn(52781) About Me  (Show Source):
You can put this solution on YOUR website!
.

Your solution is good, correct and perfect.

My congratulations - you did a perfect job !