Question

已知x1,x2是一元一次方程2x2-2x+m+1=0的两个实数根

Answer 1

(1)b^2-4ac=4-4*2*(m+1)≥0

4-8m-8≥0

m≤-1/2

(2)x1+x2=1

x1x2=(m+1)/2

x1^2+x2^2=(x1+x2)^2-2x1x2=1-1-m=-m

7+2m+2>-m

9>-3m

m>-3

-3