Suatu fungsi dirumuskan dengan f(x) =ax+b. Jika f(-3)=-7 dan f(2)=13,maka nilai f(5) adalah... a. 25 b. 31 c. 36 d. 40

rumus fungsi = f(x) = ax + b
f(x) = ax + b = c
*f(-3) = a(-3) + b = -7
= -3a + b = -7 ... pers 1

*f(2) = a(2) + b = 13
= 2a + b = 13 ... pers 2

Eliminasi pers 1 dan 2 :
-3a + b = -7
2a + b = 13
__________ -
-5a + 0 = -20
-5a = -20
a = -20/-5
a = 4

Subsitusi a = 4 ke pers 1 :
-3a + b = -7
-3(4) + b = -7
-12 + b = -7
b = -7 + 12
b = 5

Mak hasil persamaan yang baru di dapat yaitu 4x + 5

sehigga fungsi baru f(x) = 4x + 5 :
f(x) = 4x + 5
f(5) = 4(5) + 5
= 20 + 5
= 25 In answer is opsi a

So math is so easy and simple...

f(x) = ax+b.
f(-3)=-7 <=> -7= a.-3 +b <=> -7= -3a+b
f(2) = 13<=> 13= a.2 +b <=> 13= 2a +b

Eliminasi
1. -7= -3a+b
2. 13= 2a+b
_________-
-20= -5a+0
-20= -5a
-20/-5 =a <=> a= 4

substitusi
-7= -3a+b
-7= -3.4+b
-7=-12+b
b=-12+-7
b=5

f(5)=ax+b
=4.5+5
=20+5
=25
Jawabannya a. 25