Question

Resolva as equações

a)
$20x - 4 = 5x$
b)
$4x = - 8x + 36$
c)
$4( \times - 3) = 2x - 5$
d)
$5(1 - x) - 2x + 1 = - 3(2 + x)$
e)
$7x - 3 = x + 5 - 2x$
f)
$x - 3 = 5$
g)
$x + 2 = 7$
h)
$x - 7 = - 7$
i)
$x - 109 = 5$
j)
$15 = x + 1$

Answer 1

a)

$20x-4=5x\\\\ 20x-5x=4\\\\ 15x=4\\\\ \displaystyle x=\frac{4}{15}$

b)

$4x=-8x+36\\\\ 4x+8x=36\\\\ 12x=36\\\\ \displaystyle x=\frac{36}{12}\\\\ x=3$

c)

$4(x-3)=2x-5\\\\ 4x-12=2x-5\\\\ 4x-2x=-5+12\\\\ 2x=7\\\\ \displaystyle x=\frac{7}{2}$

d)

$5(1-x)-2x+1=-3(2+x)\\\\ 5-5x-2x+1=-6-3x\\\\ -7x+6=-6-3x\\\\ -7x+3x=-6-6\\\\ -4x=-12\\\\ 4x=12\\\\ \displaystyle x=\frac{12}{4}\\\\ x=3$

e)

$7x-3=x+5-2x\\\\ 7x-3=-x+5\\\\ 7x+x=5+3\\\\ 8x=8\\\\ \displaystyle x=\frac{8}{8}\\\\ x=1$

f)

$x-3=5\\\\ x=5+3\\\\ x=8$

g)

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

h)

$x-7=-7\\\\ x=-7+7\\\\ x=0$

i)

$x-109=5\\\\ x=5+109\\\\ x=104$

j)

$15=x+1\\\\ 15-1=x\\\\ 14=x\\\\ x=14$