Question

Calcule: (x+9) ² = (x+3) ² + (2x) ² teorema de pitagoras

Answer 1

(x+9) ² = (x+3) ² + (2x) ²

x²+18x+81 =x²+6x+9+4x²

18x+81 =6x+9+4x²

18x+72 =6x+4x²

72 =-12x+4x²

4x²-12x-72=0   ..divida tudo por 4

x²-3x-18=0

x'=[3+√(9+72)]/2 =6
x''=[3-√(9+72)]/2 =-1