Question

已知关于x的方程x²+2（m+2）x+m²-5=0=0有两个实数根,并且这两个根的平方

Answer 1

x1,x2为两根

x1+x2=-2(m+2) x1*x2=m^2-5

x1^2+x2^2=x1*x2+16

(x1+x2)^2=3x1*x2+16

4(m+2)^2=3(m^2-5)+16

4m^2+16m+16=3m^2+1

m^2+16m+15=0

(m+1)(m+15)=0

m1=-1 m2=-15