若x1、x2是方程x²+3x-5=0的两个根,则(x1+1)(x2+1)的值为 A.-7 B.-1 C.-1+更29.D.-1-根29
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![若x1、x2是方程x²+3x-5=0的两个根,则(x1+1)(x2+1)的值为 A.-7 B.-1 C.-1+更29.D.-1-根29](/uploads/image/z/13200326-62-6.jpg?t=%E8%8B%A5x1%E3%80%81x2%E6%98%AF%E6%96%B9%E7%A8%8Bx%26%23178%3B%2B3x-5%3D0%E7%9A%84%E4%B8%A4%E4%B8%AA%E6%A0%B9%2C%E5%88%99%EF%BC%88x1%2B1%EF%BC%89%EF%BC%88x2%2B1%EF%BC%89%E7%9A%84%E5%80%BC%E4%B8%BA+A.-7+B.-1+C.-1%2B%E6%9B%B429.D.-1-%E6%A0%B929)
若x1、x2是方程x²+3x-5=0的两个根,则(x1+1)(x2+1)的值为 A.-7 B.-1 C.-1+更29.D.-1-根29
若x1、x2是方程x²+3x-5=0的两个根,则(x1+1)(x2+1)的值为 A.-7 B.-1 C.-1+更29.D.-1-根29
若x1、x2是方程x²+3x-5=0的两个根,则(x1+1)(x2+1)的值为 A.-7 B.-1 C.-1+更29.D.-1-根29
根据韦达定理有
x1+x2=-3
x1*x2=-5
(x1+1)(x2+1)=x1x2+x1+x2+1=-5-3+1=-7
所以选A
x1+x2=-3
x1x2=-5
原式=x1x2+x1+x2+1=-5-3+1=-7
选A