Question

(3X^2-XY-2Y^2)-2(X^2+XY-2Y^2) 2丨x-3丨+7=15

Answer 1

(3X^2-XY-2Y^2)-2(X^2+XY-2Y^2)

=3X^2-XY-2Y^2-2X^2-2XY+4Y^2

=X^2-3XY+2Y^2

解方程2|x-3|+7=15

2|x-3|=8

|x-3|=4

x-3=-4,x-3=4

x=-1,x=7