已知x-y=5 求x^2-y^2-10y+3_其他解答

已知x-y=5 求x^2-y^2-10y+3

人气：413 ℃　时间：2020-06-18 00:37:00

解答

x-y=5
x^2-y^2-10y+3
=(x+y)(x-y)-10y+3
=5(x+y)-10y+3
=5x+5y-10y+3
=5x-5y+3
=5(x-y)+3
=5×5+3
=28