Question

当(a+2b)/(2a-3b)=2时求代数式(4b+2a)/(9b-6a)-(4a-6b)/(3a+6b)的值

Answer 1

(4b+2a)/(9b-6a)-(4a-6b)/(3a+6b)

=2(a+2b)/[-3(2a-3b)]-2(2a-3b)/3(a+2b)

=-2/3 ×[(a+2b)/(2a-3b)] -2/3 [(2a-3b)/(a+2b)]

=-2/3×2 -2/3×1/2

=-5/3