Question

1.已知m+n=3,mn=2,求—3(1/3n—mn)+2(mn—1/2m）.

Answer 1

1.

—3(1/3n—mn)+2(mn—1/2m）＝（3mn^2-1）/n + （2nm^2-1）/m

=5mn-(m+n)/(mn)=5x2-3/2=10-1.5=8.5

2.

当x=-2,y=a(-2)^5+b(-2)^3+c(-2)—1＝－（a2^5+b2^3+c2）-1 =5

所以a2^5+b2^3+c2=-5-1＝-6

当x=2,y=a2^5+b2^3+c2—1＝-6-1＝-7