Question

va rog eu mult dau 70÷2 de puncte ..dacă le puteti pe toate

Answer 1

$21) \\ \\ a) \frac{x + 1}{2} - \frac{x - 1}{5} = 6 \\ \\ 5(x + 1) - 2(x - 1) = 60 \\ \\ 5x + 5 - 2x + 2 = 60 \\ \\ 3x + 7 = 60 \\ \\ 3x = 60 - 7 = 53 \\ \\ x = \frac{53}{3}$

$b) \frac{2x + 1}{3} + 3x = \frac{5}{2} \\ \\ 2x + 1 + 9x = \frac{15}{2} \\ \\ 11x + 1 = \frac{15}{2} \\ \\ 11x = \frac{15}{2} - 1 \times \frac{2}{2} = \frac{15}{2} - \frac{2}{2} = \frac{15 - 2}{2} \\ \\ 11x = \frac{13}{2} \\ \\ x = \frac{ \frac{13}{2} }{11} = \frac{13}{2 \times 11} = \frac{13}{22}$

$c) \frac{x - 1}{2} + 3(x + 1) = \frac{5x}{3} \\ \\ 3(x - 1) + 18(x + 1) = 10x \\ \\ 3x - 3 + 18x + 18 = 10x \\ \\ 21x + 15 = 10x \\ \\ 15 = 10x - 21 \\ \\ 15 = - 11x \\ \\ - \frac{15}{11} = x \\ \\ x = - \frac{15}{11}$

22)

a)3x-2≤13

3x≤13+2

3x≤15

x≤$\frac{15}{3}$

x≤5

b)2-3x<3-x

-3x-3-x-2

-3x<1-x

-3x+x<1

-2x<1

$x > - \frac{1}{2}$

c)4(x-1)+3≥11

4(x-1)≥11-3

4(x-1)≥8

x-1≥$\frac{8}{4}$

x-1≥2

x≥2+1

x≥3

d)5-3(x+1)>2x-6

5-3x-3>2x-6

-3x+2>2x-6

2>2x-6+3x

2>5x-6

2+6>5x

8>5x

$\frac{8}{5} > x \\ \\ x < \frac{8}{5}$

20)

a)2x+3(x-3)=1

2x+3x-9=1

5x-9=1

5x=1+9=10

$x = \frac{10}{5} = 2$

b)3(x+1)-2(x+3)=5

3x+3-2x-6=5

x-3=5

x=5+3=8

c)5x-7=2(x+3)

5x-7=2x+6

5x=2x+6+7

5x=2x+13

5x-2x=13

3x=13

$x = \frac{13}{3}$