Answer:
Step-by-step explanation:
delta=( m-3)^2+4*5
pt có 2 nghiệm x1 x2 khi delta>0<=>(m-3)^2+20>0(luôn đúng)
Viet: x1+x2=3-m
x1x2=-5
x1^{2} +x2^{2} -5x1x2+3x1+3x2=4
<=>(x1+x2)^{2}-7x1x2+3(x1+x2)=4
<=>(3-m)^2+35+3*(3-m)=4
<=>m^2-6m+9+35-3m+9-4=0
<=>m^2-9m+49=0
