Question

Diketahui fungsi f(x)= 3x + 10. jika f(-1) = a dan f(b)= -2, maka nilai a+b adalah.......
a.3
b.7
c.11
d.13

Answer 1

F(-1) = a = 3(-1) + 10 = 7
f(b) = -2 = 3b + 10
         -12 = 3b
         -4 = b
 a + b = 7 + (-4) = 3 (A.)

Answer 2

F(-1) = a
3×-1+10 =a
-3+10=7
a = 7

f(b) = -2
3x+10 = -2
3×b + 10 = -2
3b= -2 - 10
b = -12/3 = -4
b = -4

a + b = 7 +(-4) =3