Question

Si a+b= 12; a2+b2=120. Hallar ab

Answer 1

Respuesta:

$(x + y) {}^{2} = x {}^{2} + 2xy + y {}^{2}$

entonces

(a+b)^2= a^2 +2ab+ b^2

(12)^2= 120+2ab

144=120+2ab

24=2ab

12=ab