Question

Rezolvati, in multimea numerelor reale, ecuatia
3(x+5)-5(1-x)(1+x)=(x+3)^2+(2x-1)^2+13.

Answer 1

3(x+5)-5(1-x)(1+x)=(x+3)^2+(2x-1)^2+13  unde  x∈R ...
↓
3x+15 - 5(1²-x²) = x²+6x+9 + 4x²-4x+1 + 13
3x+15 - 5 + 5x² = x²+6x+9 + 4x² - 4x +1 +13   (ordonam ecuatia ...)
5x²-x²-4x² +3x-6x+4x = 1+13 -15+9
                   ------------
                        ↓
                        x = 8 ∈ R