Question

设a-b=3,c-b=3分之1,求代数式3(a-c)^2+2(c-a)-5的值

Answer 1

a-b=3,c-b=3分之1

则a-b-(c-b)=3-3分之1

所以a-c=3分之8

3(a-c)^2+2(c-a)-5

=3(a-c)^2-2(a-c)-5

=[3(a-c)-5][(a-c)+1]

=(8-5)×(3分之8+1)

=11