Question

Diketahui f(x) = 2x kuadrat + bx +1 . Jika f(-1) =6 , nilai b adalah?

Answer 1

F(-1)= 2. -1kuadrat + b.-1 +1 =6
2-b+1= 6
3-b=6
-b=6-3
b=-3

Answer 2

F(x) = 2x² +bx +1
f(-1) = 2(-1)² +b(-1) +1 = 6
       = 2(1) +(-b) +1 = 6
       = 2 +(-b) +1 = 6
       = -b = 6 -2 -1
       = -b = 3
       = b = -3

Jadi, nilai b adalah -3.