Suatu fungsi dirumuskan f(x)=ax+b jika f(-2)=13 dan f(3) = -7 maka nilai f(-3) adalah?

[tex]f(x) = ax + b \\ \\ f( - 2) = - 2a + b = 13 \\ f( \: 3 \: ) \: = \: \: \: \: \:3a + b = - 7 \\ - - - - - - - - - - - (- ) \\ - 5a = 20 \\ a = - 4 \\ \\ - 2a + b = 13 \\ - 2( - 4) + b = 13 \\ b = 13 - 8 \\ b = 5 \\ \\ f(x) = - 4x + 5 \\ \\ f( - 3) = - 4( - 3) + 5 \\ f( - 3) = 12 + 5 \\ f( - 3) = 17[/tex]

jawab

f(x) = ax + b

f(-2) = 13
f(3) = - 7 ......(-)
(-2 - 3)a = 13 -(-7)
-5a = 20
a = - 4

f(3)  = - 7
b = -7 - 3a
b = - 7 -3(-4)
b = 5

F(-3) = - 3a  + b
= - 3(-4) + 5
= 12 + 5
= 17