Question

已知x的平方-4y的平方=20,x+2y=5,求x,y的值

Answer 1

x的平方-4y的平方=20,==>X^2-4Y^2=20 ==>(X+2Y)(X-2Y)=20

x+2y=5,(1)

==>X-2Y=4 (2)

(1)+(2).2X=9 ==>X=9/2

(1)-(2).4Y=1 ==>Y=1/4