Question

Calcule x :
quero a conta

Answer 1

_√x + 1_ + _x_= _17_
      3          10         6
10√(x + 1) + 3x = 85
[10√(x + 1)]² = (85 - 3x)²
100(x + 1) = 7225 - 510x + 9x²
9x²  - 610x +7125 = 0
x = _610+-√[(610)² - 4(9)(7125)]_
                       2(9)
x = _610+-√372100 - 256500_
                      18
x = _610 +-√115600_
                   18
x = _610 +- 340_
             18
x' = _610 + 340_ ⇒ x' = _950_ ⇒ x' = _475_
                18                     18                   9
x'' = _610 - 340_ ⇒ x'' =_ 270_ ⇒ x'' = _30_ ⇒ x'' = 15
             18                         18                  2
 somente x = 15 satisfaz a equação
Resposta: 15