Question

1.若2^a=3,2^b=30,试用a,b表示c=?

Answer 1

1.若2^a=3,2^b=30,试用a,b表示c=?

c是什么?

2.x^2-y^2=(x+y)(x-y)=27

x+y=27/(x-y)=9

x-y=3

2x=12

x=6,y=3

y/x=1/2

3.已知a+4b=2,

-2^a * 16^b=-2^a * (2^4)^b

=-2^a*2^4b

=-2^(a+4b)

=-2^2

=-4

4.(2x-3y)^2 * (2x+3y)^2

=[(2x-3y)* (2x+3y)]^2

=(4x^2-9y^2)^2

=16x^4-72x^2y^2+81y^2