Question

escreva a função afim f(x)= ax+b, sabendo que: f (-3)=9 e f (5)= -7

Answer 1

$f(-3)=9 \\ \\ -3a+b=9 \\ \\ f(5)=-7 \\ 5a+b=-7 \\ \\ \left \{ {{-3a+b=9} \atop {5a+b=-7}} \right. \\ \\ \left \{ {{-3a+b=9} \atop -5a-b=7}} \right. \\ \\ -3a-5a+b-b=9+7 \\ \\ -8a=16 \\ \\ a=- \frac{16}{8} =-2 \\ \\ \\ -3a+b=9 \\ \\ -3.(-2)+b=9 \\ \\ b=9-6=3 \\ \\ \\ f(x)=-2x+3$