Question

como é a conta 8x(ao quadrado)=60 -7x(ao quadrado) ?

Answer 1

$8 x^{2} =60-7 x^{2} \to \\\\8 x^{2} +7 x^{2} =60\to \\\\15 x^{2} =60\to \\\\ x^{2} = \frac{60}{15} \to \\\\ x^{2} =4\to\\\\ x=+- \sqrt{4} \to \\\\ x=+-2\\\\\\\\ x'=-2\\x''=+2\\\\\\ S=(-2;2)$