Question

6x²-(4x²-7x+5)-(-3x+3x²-7)

Answer 1

Sempre comece esse tipo de exercício organizando banana com banana e maçã com maçã
$6 x^{2} -4 x^{2} +3 x^{2} = 5 x^{2}$

$3x - 7x = -4x$

$5 - 7 = -2$

Resultado : $5x^{2} - 4x -2$

Answer 2

$6x^2-(4x^2-7x+5)-(-3x+3x^2-7)\\\\ 6x^2-4x^2+7x-5+3x-3x^2+7\\\\ (6x^2-4x^2-3x^2)+(7x+3x)+(-5+7)\\\\ -x^2+10x+2\ \ (\times -1)\\\\ \boxed{x^2-10x-2}$

$Termos:\\ a = 1\ \ \ \ b=-10\ \ \ \ c=-2\\\\\\ Resolvendo\ por\ f\'ormula\ de\ Bh\'askara:\\\\\\ x=\dfrac{-b\pm\sqrt{b^2-4ac}}{2a}\\\\ x=\dfrac{10\pm\sqrt{100-(4*1*-2)}}{2*1}\\\\ x=\dfrac{10\pm\sqrt{100+8}}{2}\\\\ x=\dfrac{10\pm6\sqrt{3}}{2}\\\\ x=5\pm3\sqrt{3}\\\\\\ Raizes:\\ \boxed{x'=5+3\sqrt{3}} \boxed{x''=5-3\sqrt{3}}$

Bons estudos!