what is the value of β?

Question

If f(x)=3x^2 + βx + 4 and f(−1) = 12,what is the value of β?

Answer 1

f(x)   =   3x^2 + βx + 4

Substitute x = -1 in above function

f(-1)   =   3(-1)^2 + β(-1) + 4

12   =   3(1) - β + 4             [ Since f(-1)  =  12 ]

β   =   7 - 12

β   =  - 5

The solution is β   =  - 5.