Question

Di ketahui f(×) =3×+10,
jika f(-1)=a dan f(b)=-2, nilai a+b adalah
a.-3
b.-1
c. 1
d.3

pakai cara ..

Answer 1

F(x) = 3x + 10
f(-1) = a
f(b) = -2

f(-1) = 3 * -1 + 10
a = -3 + 10
a = 7

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

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

Answer 2

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