Question

Reduza os polinômios abaixo indefique qual o grau da equação formadaa:
(2×+3) .(5)=7×

b: (×-3) .(4+×)=3ײ-5

c: (2×-3²=12​

Answer 1

a)

$\left(2x+3\right)\left(5\right)=7x\\\\10x+15=7x\\\\10x+15-15=7x-15\\\\10x=7x-15\\\\10x-7x=7x-15-7x\\\\3x=-15\\\\\frac{3x}{3}=\frac{-15}{3}\\\\x=-5$

b)

$\left(x-3\right)\left(4+x\right)=3x^2-5\\\\x+x^2-12+5=3x^2-5+5\\\\x^2+x-7=3x^2\\\\x^2+x-7-3x^2=3x^2-3x^2\\\\x_{1,\:2}=\frac{-1\pm \sqrt{1^2-4\left(-2\right)\left(-7\right)}}{2\left(-2\right)}\\\\x_{1,\:2}=\frac{-1\pm \sqrt{55}i}{2\left(-2\right)}\\\\x_1=\frac{-1+\sqrt{55}i}{2\left(-2\right)},\:x_2=\frac{-1-\sqrt{55}i}{2\left(-2\right)}\\\\x=\frac{1}{4}-i\frac{\sqrt{55}}{4},\:x=\frac{1}{4}+i\frac{\sqrt{55}}{4}$

c)

$2x-3^2=12\\\\2x-9=12\\\\2x-9+9=12+9\\\\2x=21\\\\\frac{2x}{2}=\frac{21}{2}\\\\x=\frac{21}{2}$