Question

Suatu fungsi dirumuskan f(x)=ax+b.Jika f(-2)=13 dan f(x)=-7,maka nilai f(-3)adalah

Answer 1

F(x) = ax + b
f(-2) = a(-2) + b = 13
13 = -2a + b
13 + 2a = b .......... (persamaan 1)
f(3) = a(3) + b = -7
-7 = 3a + b ........... (persamaan 2)

3a + b = -7
3a + (13 + 2a) = -7
3a + 13 + 2a = -7
3a + 2a = -7 -13
5a = -20
a = -20/5
a = -4

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

f(x) = ax + b
f(x) = -4x + 5

f(-3) = -4(-3) + 5
f(-3) = 12 + 5
f(-3) = 17