Diketahui rumus fungsi f(x)=-4x+9. Jika f(a)=1 dan (3)=, maka nilai a-b adalah

F(a) = 1
-4a + 9 = 1
-4a = 1 – 9
-4a = -8
a = -8 ÷ -4 = 2

f(3) = b
-4(3) + 9 = b
-12 + 9 = b
-3 = b

a – b = 2 – (-3) = 2 + 3 = 5

Diketahui :
f(x) = -4x + 9
f(a) = 1
f(3) = b

Ditanya :
a – b?

Jawab :
f(x) = -4x + 9
f(a) = -4a + 9
1 = -4a + 9
4a = 8
a = 2

f(x) = -4x + 9
f(3) = -4(3) + 9
b = -12 + 9
b = -3

= a – b
= 2 – (-3)
= 5