Question

数学分式整式题1.a+1/a=10,求(a-1/2)的平方2.a^m=3 a^n=2,求a^2m-n3.已知1/a-1/

Answer 1

1.(a-1/a)^2

=a^2-2*a*(1/a)+(1/a^2)

=a^2+(1/a)^2-2

=[a+(1/a)]^2-2*a*(1/a)-2

=10^2-4

=96;

2.a^(2m-n)

=a^(2m)/(a^n)

=(a^m)^2/(a^n)

=3^2/2

=9/2;

3.因为1/a-1/b=4,

所以(b-a)/(ab)=4,

所以b-a=4ab,

所以a-b=-4ab,

所以(a-2ab-b)/(2a-2b+7ab)

=[(a-b)-2ab]/[2(a-b)+7ab]

=(-4ab-2ab)/(-8ab+7ab)

=-6ab/(-ab)

=6.