Question

Решите пожалуйста номер 204, 3 уравнение, 4, 5, 6

Answer 1

1.
5(x-4)=x+8
5x-20=x+8
5x-x=8+20
4x=28
x=7

2.
9-7(x+3)=5-6x
9-7x-21=5-6x
9-21-5=-6x+7x
x=-17

3.
(7x+9)-(11x-7)=8
7x+9-11x+7=8
7x-11x=-9-7+8
-4x=-8
x=2

4.
3.6+5y=7(1.2-y)
3.6+5y=8.4-7y
5y+7y=8.4-3.6
12y=4.8
y=0.4

5.
0.4(6-4t)=0.5(7-3t)-1.9
2.4-1.6t=3.5-1.5t-1.9
-1.6t+1.5t=-2.4+3.5-1.9
-0.1t=-0.8
t=8

6.
$\frac{3}{4}(\frac{1}{6}x-\frac{1}{3})=3x-11\frac{1}{2}$
$\frac{3}{24}x-\frac{3}{12}=3x-11\frac{1}{2}$
$\frac{1}{8}x-\frac{1}{4}=3x-11\frac{1}{2}$
$-\frac{1}{4}+11\frac{1}{2}=3x-\frac{1}{8}x$
$-\frac{1}{4}+11\frac{2}{4}=2\frac{7}{8}x$
$11\frac{1}{4}=2\frac{7}{8}x$
$11\frac{2}{8}=2\frac{7}{8}x$
$\frac{90}{8}=\frac{23}{8}x$
$x=\frac{90}{8}\div\frac{23}{8}=\frac{90}{8}\times\frac{8}{23}=\frac{90}{23}$