f(x)=ax+b. jika f(-2)= -13 dan f(2)=3 maka nilai f(15) adalah?

f(-2) = -2a + b = -13
f(2) = 2a + b = 3

kemudian di eliminasi

-2a + b = -13
2a + b = 3
_________-
-2a -2a = -13 - 3
-4a = -16
a = -16/-4
a = 4

kemudian cari b dengan cara subtitusi

2a + b = 3
2 x 4 + b = 3
8 + b = 3
b = 3 - 8
b = -5

sekarang cari f(15)
= 15a + b
= 15 x 4 + (-5)
= 60 - 5
= 55

Rumus f(x)=ax+b
-2a+b=-13
2a+b=3 -
-------------
-4a=-16
a=-16/-4=4

2a+b=3
2(4)+b=3
8+b=3
b=3-8=-5

f(15)=ax+b
4(15)+(-5)
60-5=55