Question

8的三次方等于a的九次方等于二的b次方，求（a-0.2b)^2+(a+0.2b)^2-2b(a^2+0.02b)的值。

Answer 1

a^9=8^3=(2^3)^3=2^9
所以a=2
2^b=8^3=2^9
所以b=9
所以（a-0.2b)^2+(a+0.2b)^2-2b(a^2+0.02b)
=(2-0.2*9)²+(2+0.2*9)²-2*9(2²+0.02*9)
=0.2²+3.8²-18*(4+0.18)
=0.04+14.44-18*4.18
=14.48-75.24
=-60.76

Answer 2

8x8x8=512=2x256=2x2x128=2x2x2x64=2x2x2x2x2x2x2x2x2 b=9 axaxaxaxaxaxaxaxa=512
a=2
原式=a²-0.4ab+0.04b²+a²+0.4ab+0.04b²-2a²b-0.04b²
=2a²+0.04b²-2a²b
=8+1.44-72
=-62.56

Answer 3

因为8的3次方=2^9，所以a=2，b=9，原式=0.04+3.8^2-18*4.18,答案就按计算机吧

Answer 4

8²=2^9
所以a=2,b=9

原式=a²-0.4ab+0.04b²+a²+0.4ab+0.04b²-2a²b-0.04b²
=2a²+0.04b²-2a²b
=8+1.44-72
=-62.56

Answer 5

因为
|3a+1|>=0,(2b-1)²>=0
|3a+1|+(2b-1)²=0,
所以：3a+1=0,2b-1=0
a=-1/3,b=1/2
(3a^2-2b^3)/ab
=7/2