Suatu fungsi ditentukan dengan rumus f(x)=ax+b, jika f(3)=7 dan f(-2)=-3. Hitung nilai a+b!

a.3+b=7
a.-2+b=-3

Eliminasi
3A+B=7. ||.1
-2A+B=-3||.1
_________
A = 4

Subtitusi
4(3)+b =7
12+b=7
b=7-12
b=-5

f(x) = ax + b
f(3) = 7
f(-2) = -3

f(x) = ax + b
f(3) = a(3) +b
7 = 3a + b (persamaan 1)

f(x) = ax + b
f(-2) = a(-2) + b
-3 = -2a + b (persamaan 2)

3a + b = 7
-2a + b = -3
------------------- -
5a = 10
a = 10/5
a = 2

3a + b = 7
3(2) + b = 7
6 + b = 7
b = 7 - 6
b = 1

a + b
= 2 + 1
= 3