设x1、x2是方程是2x^2+4x-3=0的两个根,利用根与系数的关系,求下列各式的值:1、(x1+1)(x2+1) 2、x1^2x2+x1x2^2 3、x2/x1+x1/x2 4、(x1-x2)^2

问题描述:

设x1、x2是方程是2x^2+4x-3=0的两个根,利用根与系数的关系,求下列各式的值:
1、(x1+1)(x2+1) 2、x1^2x2+x1x2^2 3、x2/x1+x1/x2 4、(x1-x2)^2

x1+x2=-2 x1x2=-3/2
1)(x1+1)(x2+1)=x1x2+x1+x2+1=-2.5
2)=x1x2(x1+x2)=3
3)=「(x1+x2)²-2x1x20」/x1x2=-3.5
4)=(x1+x2)²-4x1x2=10

x1+x2=-2
x1*x2=-3/2
1、(x1+1)(x2+1)
=x1*x2+(x1+x2)+1
=-3/2-2+1
=-5/2
2、x1^2x2+x1x2^2
=x1*x2(x1+x2)
=(-3/2)*(-2)
=3
3、x2/x1+x1/x2
=(x2^2+x1^2)/(x1*x2)
=[(x1+x2)^2-2x1x2]/(x1*x2)
=[(-2)^2+3]/(-3/2)
=-14/3
4、(x1-x2)^2
=(X1+X2)^2-4x1x2
=4+6
=10

(x1+1)(x2+1)= x1x2 + x1 + x2 + 1= (-3/2) + (-4/2) + 1= -5/2x1^2x2+x1x2^2= (x1x2)(x1+x2)= (-3/2)(-4/2)= 3x2/x1+x1/x2= (x1^2+x2^2)/(x1x2)= (x1^2+2x1x2+x2^2-2x1x2)/(-3/2)= ((-4/2)^2-2(-3/2))/(-3/2)= -14/...

x1+x2=-4/2=-2
x1*x2=-3/2
1、(x1+1)(x2+1)=x1*x2+(x1+x2)+1=-2+(-3/2)+1=-5/2
2、x1^2x2+x1x2^2=x1*x2*(x1+x2)=-2*(-3/2)=3
3、x2/x1+x1/x2
=(x1^2+x2^2)/(x1*x2)
=[(x1+x2)^2-2x1*x2]/(x1*x2)
=(x1+x2)^2/(x1*x2) -2
=(-2)^2/(-3/2)-2
=-14/3
4、(x1-x2)^2=(x1+x2)^2-4x1*x2=(-2)^2-4*(-3/2)=10