Question

Resolva as equações de 2° grau do tipo ax2 =b,com U=R

a) 9x2 =36

b) x² +28 =2x² +3

c) 15x² +5 =31x ² + 4

d) x²-1/12=4

me ajudemm porfavor 100 pontos

Answer 1

A)

$9x^{2} = 36\\x^{2} = \frac{36}{9} \\x^{2} = 4\\\sqrt{x^{2} } = \sqrt{4} \\x= \sqrt{4} \\x=2$

B)

vamos manipular.

x² +28 =2x² +3

$2x^{2} - x^{2} = 28-3 \\x^{2} = 25 \\\sqrt{x^{2} } = \sqrt{25} \\x= \sqrt{25} \\x=5$

C)

15x² +5 =31x ² + 4

$31x^{2} - 15x^{2} = 5-4\\16x^{2} = 1\\x^{2} = \frac{1}{16} \\\sqrt{x^{2} } = \sqrt{\frac{1}{16} } = \frac{\sqrt{1} }{\sqrt{16} } = \frac{1}{4} \\x= \frac{1}{4}$

D)

$\frac{x^{2} -1}{12} = 4\\x^{2} -1= 48\\x^{2} = 49\\\sqrt{x^{2} } = \sqrt{49} \\x=7$