suatu fungsi dirumuskan f(x) =ax+b. jika f(-2)= 14 dan f(3)= -1 nilai f(7) adalah

f(x) = ax+b

f(-2) = 14 ==> -2a + b = 14
f(3) = -1 ==> 3a + b = -1

3a + b = -1
-2a + b = 14
---------------- -
5a = -15
a = -15/5
a = -3

3a + b = -1
3.-3 + b = -1
-9 + b = -1
b = 9 - 1
b = 8

f(x) = ax+b
f(x) = -3x+8
f(7) = -3.7+8 = -21 + 8 = -13