Question

Como resolvo essa conta de 2 graus
(14x-9)²=225

Answer 1

Resolução da questão, veja:

Como 225 é quadrado perfeito, (Possui raiz exata), podemos aplicar a raiz quadrada em ambos os lados da equação a fim de eliminar o expoente do lado esquerdo, vejamos:

$\mathtt{(14x-9)^{2}}}\mathtt{=225}}}}}}}\\\\\\\\\\ \mathtt{\sqrt{(14x-9)^{2}}}}\mathtt{=\sqrt{225}}}}}}}}}}\\\\\\\\\\ \mathtt{14x-9=~\pm~15}}}}}}\\\\\\\\ \mathtt{14x=15+9}}}\\\\\\\ \mathtt{14x=24}}}}}\\\\\\\\ \mathtt{x=\dfrac{24}{14}}}}\\\\\\\\\\ \Large\boxed{\boxed{\mathbf{x=\dfrac{12}{7}}}}}}}}}}}}}}\\\\\\\\\ \mathtt{14x-9=-15}}}\\\\\\\\\ \mathtt{14x=-15+9}}}\\\\\\\\ \mathtt{14x=-6}}}\\\\\\\\\\ \mathtt{x=\dfrac{-6}{14}}}}}}}\\\\\\\\\\\\ \Large\boxed{\boxed{\boxed{\mathbf{x=\dfrac{-3}{7}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}}$

Espero que te ajude. '-'