Question

a) 7x^2 + 2 = 30
b) 3(x^2 – 1) = 24
c)2x^2 – 90 = 8
d) 5(x^2 – 1) = 4(x^2 + 1)

Answer 1

Resposta:

a) 2

b) 3

c) 7

d) 3

Explicação passo-a-passo:

a)

$7x^{2} + 2 = 30\\7x^{2} = 30 - 2\\7x^{2} = 28\\x^{2} = 28/7\\x^{2} = 4\\\sqrt {x^{2} } = \sqrt{4} \\x = 2$b)

$3(x^2 - 1) = 24\\3x^{2} - 3 = 24\\3x^{2} = 24 + 3 \\3x^{2} = 27\\x^{2} = 27/3\\x^{2} = 9\\\sqrt{x^{2} } = \sqrt{9} \\x = 3$

c) $2x^2 - 90 = 8\\2x^2 = 8 + 90 \\2x^2 = 98 \\x^{2} = 98/2\\x^{2} = 49\\\sqrt{x^{2} } = \sqrt{49} \\x = 7$

d) $5(x^2 - 1) = 4(x^2 + 1) \\5x^{2} - 5 = 4x^{2} + 4\\5x^{2} - 4x^{2} = 4 + 5 \\x^{2} = 9 \\ \sqrt{x^{2} } = \sqrt{9} \\x = 3$