设X1、X2是一元二次方程2X^2-5X+1=0的两个根,利用根与系数的关系,求下列各式的值 (要详细过)(1)(X1-3)(X2-3)
问题描述:
设X1、X2是一元二次方程2X^2-5X+1=0的两个根,利用根与系数的关系,求下列各式的值 (要详细过)
(1)(X1-3)(X2-3)
答
x1+x2=5/2 x1x2=1/2
(X1-3)(X2-3)
=x1x2-3(x1+x2)+3
=1/2-15/2+9
=-7+9
=2
答
x1+x2=5/2
x1x2=1/2
(1)(X1-3)(X2-3)
=x1x2-3(x1+x2)+9
=0.5-7.5+9
=2
答
x1+x2=5/2 x1x2=1/2
(X1-3)(X2-3)
=x1x2-3(x1+x2)+3
=1/2-15/2+9
=-7+9
=2