Question

Jika rumus f(x) = px + q
diketahui : f(-1) = -5 dan f(4) = 5
f(-3) = ...?

Answer 1

F(x)=px+q
f(-1)=px+q
-5=p(-1)+q
-p+q=-5

f(x)=px+q
f(4)=p(4)+q
5=4p+q

eliminasi
-p+q=-5
4p+q=5
>>-5p=-10 p=2
-p+q=-5
-2+q=-5
q=-3

f(-3)=p(-3)+q
=2(-3)+-3
=-6-3
=-9

Answer 2

F(x) = px + q

f(-1) = -1p + q = -5 .... (1)
f(4) = 4p + q = 5 .... (2)

substitusi dan eliminasi persamaan 1&2
-1p+q = -5
4p+q = 5
-5p = -10
p = 2

4p+q = 5
4.2+q=5
8+q=5
q=5-8
q= -3

f(x) = px+q
f(-3) = 2 . (-3) + (-3)
= (-6)+(-3)
= -9

(semoga membantu)