⇔3x2+6xy+14y2+7xy=330⇔3x(x+2y)+7y(x+2y)=330⇔3x2+6xy+14y2+7xy=330⇔3x(x+2y)+7y(x+2y)=330
⇔(x+2y)(3x+7y)=330⇔(x+2y)(3x+7y)=330
⇔(x+2y)(3x+7y)=330.1=165.2=10.33=5.66=15.22⇔(x+2y)(3x+7y)=330.1=165.2=10.33=5.66=15.22
x,y nguyên dương => 3x+7y > x+3y>2
TH1: {x+2y=103x+7y=33⇔{x=4y=3(n){x+2y=103x+7y=33⇔{x=4y=3(n)
TH2: {x+2y=53x+7y=66⇔{x=−97y=51(l){x+2y=53x+7y=66⇔{x=−97y=51(l)
TH3:{x+2y=153x+7y=22⇔{x=61y=−23{x+2y=153x+7y=22⇔{x=61y=−23 (l)
⇒x=4;y=3