Question

Resolva as equações e obtenha a solução de cada uma das suas incognitas.
a)x – 5 = -7
b)y - 6 = 5y + 8
d) 2x + 5 - x = 5 - 3 x
c)10 x = 20 + 9 x
f) 2 x + 1 = 15
e) 2 m + 6 = m
h) x + 6 = 2 - 3 x
9) 5 - x - 20 = 5x - 10 - 7 x​

Answer 1

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a)

$x - 5 = -7\\x = -7 + 5\\x = -2$

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b)

$y-6=5y+8\\y-6+6=5y+8+6\\y=5y+14\\y-5y=5y+14-5y\\-4y=14\\\frac{-4y}{-4}=\frac{14}{-4}\\y=-\frac{7}{2}$

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c)

$10 x = 20 + 9 x\\10x-9x=20+9x-9x\\x=20$

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d)

$2x+5-x=5-3x\\2x+5-x-5=5-3x-5\\2x-x=-3x\\x=-3x\\x+3x=-3x+3x\\4x=0\\\frac{4x}{4}=\frac{0}{4}\\x=0$

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e)

$2m+6=m\\2m+6-6=m-6\\2m=m-6\\2m-m=m-6-m\\m=-6$

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f)

$2x+1=15\\2x+1-1=15-1\\2x=14\\\frac{2x}{2}=\frac{14}{2}\\x=7$

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g)

$5 - x - 20 = 5x - 10 - 7 x​\\-x+5-20=5x-10-7x\\-x-15=5x-10-7x\\x-15=5x-7x-10\\-x-15=-2x-10\\-x-15+15=-2x-10+15\\-x=-2x+5\\-x+2x=-2x+5+2x\\x=5$

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h)

$x+6=2-3\\x+6-6=2-3x-6\\x=-3x-4\\x+3x=-3x-4+3x\\4x=-4\\\frac{4x}{4}=\frac{-4}{4}\\x=-1$

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