Question

if f(x)= 3x^2-bx+4 and f(-1)=12 what is the value of b?
[show steps
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Answer 1

3(-1)^2 -(-1)b + 4 = 12
3+b = 12
b = 12-3
b = 9

Answer 2

\[f(-1)=3(-1)^2+b(-1)+4\]\[f(-1)=3+b+4 =12\]\[3+b+4=12 \rightarrow 7+b=12 \rightarrow b=5\]

Answer 3

in the first step i did, 3(-1)^2 -b(-1) not +b(-1)

Answer 4

woops , I made a stupid mistake xD . I forgot the 4 argh