Question

Diketahui rumus suatu fungsi f(x)= ax+b, f(2)=4, Dan f(-1)=-5. Nilai dari f(-5) adalah...
A. 17
B. 13
C. -13
D. -17​

Answer 1

tolong dijadikan jawaban terbaik ya. terima kasih..

btw ini soal kls 8

Answer 2

f(x) = ax + b

f(2) = a(2) + b = 4 => 2a + b = 4

f(-1) = a(-1) + b = -5 => -a + b = -5

Eliminasi

2a + b = 4

-a + b = -5

________-

3a = 9

a = 9/3

a = 3

Substitusi

2a + b = 4

2(3) + b = 4

6 + b = 4

b = 4 - 6

b = -2

f(-5) = a(-5) + b

= 3(-5) + (-2)

= -15 - 2

= -17

Jawaban: D