f) f(x)=mx-3m-5
M(m; -1) => f(m)=-1 => m^2-3m-5=-1 => m^2-3m=4 => m^2-2m+1-m-1=4 => (m-1)^2-m-1=4 => -(m-1)^2(m+1)=4 => -(m-1)(m^2-1)=4 => avem variantele:
-(m-1)=4 =>-m+1=4 => -m=3 => m=-3
m^2-1=1 => m^2=2 => m=+√2 sau -√2
-(m-1)=1 => -m+1=1 => -m=0 fals (eliminam varianta asta)
-(m-1)=2 => -m+1=2 => m=-1
m^2-1=2 => m^2=3 => m= +√3 sau -√3
deci variantele ar fi m={-3, +√2 sau -√2; -1, +√3 sau -√3}
