Question

Daca x+2y=10 , atunci (2x+6y)²= 100 ; adevarat sau fals?

Answer 1

y=(10-x)/2=>
(2x+6y)^2=(2x-(10-x)/2)^2
((5x-10)/2)^2=100
(25x^2-100x+100)/4=100
25x^2-100x+100=400
25x^2-100x-300=0
delta=40000
x1=6=> y=2=>(2x+6y)^2<100
x2=-2=>y=6=>(2x+6y)^2<100
sa verifici calculele ca poate le-am gresit.