Question

se x+2y=18 e 2x-y= 6, então o valor de x.y é:

Answer 1

x+2y=18  ==>2x+4y=36 (i)

2x-y=6 (ii)

(i)-(ii)

5y=30 ==>y=6

2x-6=6 
x=6

x* y = 6 *6=36