Question

先化简再求值{2x-3分之2乘y-(x-y)}的2次方-3分之2乘x乘y，其中x=1，y=9

Answer 1

{2x-3分之2乘y-(x-y)}的2次方-3分之2乘x乘y，
= {2x-2y/3 -x+y} ² - 2xy/3
= (x+y/3 ) ² - 2xy/3
= x² +2xy/3 + y²/9 - 2xy/3
= x² + y²/9

其中x=1，y=9
原式= 1 + 9x9/9
= 1+ 9
= 10