Question

1) If f(x) = 3x2 – Bx + 4 and f(-1) = 12, what is the value of B?

Answer 1

`B=-5`

Explanation:

we have

`f(x)=3x^(2) -Bx+4`

we know that

f(-1) is the value of the function for x=-1

so

substitute the value of x=-1 in the function and solve for B

`f(-1)=3(-1)^(2) -B(-1)+4`

we have

`f(-1)=12`

substitute

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

`12=3-B+4`

`12=7-B`

`B=7-12`

`B=-5`