Question

若a+b/2=b-2c/3=3c-a/4,求分式5a+6b-7c/8a+9b(a不等于0)的值

Answer 1

令(a+b)/2=(b-2c)/3=(3c-a)/4=k,那么

a+b=2k,

b-2c=3k,

3c-a=4k,

解此方程组,a=-11k/5,b=21k/5,c=3k/5

(5a+6b-7c)/(8a+9b)

=(-55+126-21)/(-88+188)

=50/100

=1/2