已知x₁,x₂是一元二次方程x²-(2m+3)x+m²=0的两个不相等的实数根,且满足x₁+x₂=m²,则m=
人气:246 ℃ 时间:2019-08-20 13:30:31
解答
解由x₁,x₂是一元二次方程x²-(2m+3)x+m²=0的两个不相等的实数根
即x1+x2=-b/a=2m+3
又由x1+x2=m^2
即m^2=2m+3
即m^2-2m-3=0
故(m-3)(m+1)=0
解得m=3或m=-1
当m=3时,方程为x^2-9x+9=0,其Δ=(-9)^2-4*1*9>0,即方程有2个不相等的实根
当m=-1时,方程为x^2-x+1=0,其Δ=(-1)^2-4*1*1<0,即方程无解
故m=3.
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