Question

determine a função do 1 grau f(x)=ax+b ou f(-1)=3 e f(2)=7

Answer 1

f(x) = 4/3x + 13/3

$f(x) = ax + b\\\\f(-1) = 3 \\ a(-1) + b = 3\\ -a + b = 3\\\\ f(2) = 7\\a(2) + b = 7\\2a+b=7\\\\ \left \{ {{(-a+b=3).2} \atop {2a+b=2=7}} \right. \\\left \{ {{-2a+2b=6} \atop {2a+b=2=7}} \right. \\\\ (-2a+2b=6)+(2a+b=7)=(3b=13)\\ 3b = 13\\b= \frac{13}{3} \\\\ -a+b = 3\\-a+ \frac{13}{3} =3\\(-a+ \frac{13}{3}=3).3\\-3a+13=9\\-3a=9-13\\-3a=-4\\(-3a=-4)-1\\3a=4\\a= \frac{4}{3}$