sebuah fungsi f(x)=px+q. Jika f(3)=21 dan f(-2)=-4, maka nilai f(5) adalah A. 31 B. 34 C.36 D. 40

f(3) = 3p + q =21
f(-2) = -2p + q = -4
---------------------- dikurang
5p = 25
p = 5
f(3) = 3(5) + q = 21
15 + q = 21
q = 6
f(5) = 5p+q = 5(5) + 6 = 25+6 = 31

f(x) = px + q
f(3) = 3p + q = 21
f(-2) = - 2p + q = - 4

Mencari p

3p + q = 21
- 2p + q = - 4
___________-
5p = 25
p = 5


Mencari q

3p + q = 21
3(5) + q = 21
15 + q = 21
q = 21 - 15
q = 6

Jadi f(x) = 5x + 6

f(5) = 5(5) + 6
f(5) = 25 + 6
f(5) = 31


Jawabannya A




GL!