Let two real roots be X 1 and X2. The sum of squares is expressed as:

x 1^2+x2^2 =(x 1+x2)^2-2*(x 1*x2)

Brought in: x12+x2 2 = (-k/2) 2-2 * (1-2k)/2 = 29/4.

Solve the equation:

k^2+8k-33 = 0

k = - 1 1，3

K =-1 1 no real root rounding.

To sum up: k = 3.

9.

Discriminant = b2-4bm+4m2-4a (c-m2) = b2-4bm+4m2-4ac+4am2.

= b^2-4ac -4bm + (4+4a)*m^2

Constant equals 0, which holds for any m, so the expression does not contain m:

So: 4+4a =0

-4b =0

b^2-4ac = 0

a = - 1，b = 0，c = 0