Question

如果分式(3x+5)/(x-2)=1,那么代数式(x-3)(2x-7)的值为?

Answer 1

(3x+5)/(x-2)=1

3x+5=x-2

2x=-7

x=-7/2

代回分式方程检验,分母x-2=-7/2-2=-11/2≠0,x=-7/2是方程的解.

(x-3)(2x-7)

=(-7/2 -3)[2(-7/2) -7]

=(-13/2)(-14)

=91