Răspunsuri

  • Utilizator Brainly
2014-02-01T20:09:45+02:00
4x²-9y²=20
(2x-3y)(2x+3y)=20
-5(2x+3y)=20
2x+3y=-4
2014-02-01T20:37:21+02:00
Vom folosi formula descompunerii diferentei de patrate: a² - b² = (a-b)(a+b)
4x² - 9y² = 20 <=> (2x)² - (3y)² = 20 <=> (2x-3y)(2x+3y) = 20 
                                              Noi stim ca 2x-3y = -5
 Deci (-5)(2x+3y) = 20 <=> 2x+3y = -4
2 5 2