Question

计算初二

（1）5a²b÷(-三分之一ab)×2ab²
（2）｛（x+2y)²-(x+y)(x-y)-5y²｝÷2x
（3）(-3.6×10的十次方）÷（-2×10²）²
（4）（2a-b+3)(2a-3+b)

Answer 1

解
5a²b÷(-1/3ab)×2ab²
=5a²b×(-3ab)×2ab²
=[5×(-3)×2]a^4b^4
=-30a^4b^4

[(x+2y)²-(x+y)(x-y)-5y²]÷2x
=(x²+4xy+4y²-x²+y²-5y²)÷2x
=(4xy)÷2x
=2y

(-3.6×10^10)÷(-2×10²)²
=(-3.6×10^10)÷(4×10^4)
=-0.9×10^6

(2a-b+3)(2a-3+b)
=[2a-(b-3)][2a+(b-3)]
=(2a)²-(b-3)²
=4a²-b²+6b-9

Answer 2

（1）30a^2b^2 (2)2y (3)-0.9*10^6 (4)4a^2-b^2+6b-9