1.tìm số tự nhiên x,biết:

a.2/3=x/54

b.10/x=15/6

c.2/3<x/6<1

d.1<6/x<2

giúp mik kiểm tra 2 câu này vs

a) (x+1)(x+9)=(x+3)(x+5) 

<=>x^2+10x+9=x^2+8x+15

<=>x^2+10x+9-x^2-8x-15=0

<=>9x-6=0

<=>9x=6

<=>x=6/9=2/3 => S= 2/3

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

<=>6x^2+13x+5=6x^2-16x+6

<=>6x^2+13x+5-6x^2+16x-6=0

<=>29x-1=0

<=>29x=1

<=>x=1/29

Bài 5: Tìm tổng của tất cả các số nguyên thỏa mãn: 1/ -4 < x < 3 2/ -5 < x < 5 3/ -10 < x < 6 4/ -6 < x < 5 5/ -5 < x < 2 6/ -6 < x < 0 7/ -1 ≤ x ≤ 4 8/ -6 < x ≤ 4 9/ -4 < x < 4 10/!x! < 4 11/!x!≤ 4

Bài 5: Tìm tổng của tất cả các số nguyên thỏa mãn: 1/ -4 < x < 3 2/ -5 < x < 5 3/ -10 < x < 6 4/ -6 < x < 5 5/ -5 < x < 2 6/ -6 < x < 0 7/ -1 ≤ x ≤ 4 8/ -6 < x ≤ 4 9/ -4 < x < 4 10/!x! < 4 11/!x!≤ 4

1, √x^2-5x+8<=3x-10

2, x^2-4x+3/3-2x<1-x

3, |x^2+x-2|+3x^2-3>0

4, |x+3|>=2(1+x^2)

5, |x^2-1|>x^2+2x-3

6, |2x-1|<x+2

7, 3/2-x<=1

8, 2+3x-x^2<=√4+3x-x^2

9, √x^2-5x+6<5-x

10, x^2-6>5(x+√x^2-5x)

11, |x^2-x|<=x^2-x

1, √x^2-5x+8<=3x-10

2, x^2-4x+3/3-2x<1-x

3, |x^2+x-2|+3x^2-3>0

4, |x+3|>=2(1+x^2)

5, |x^2-1|>x^2+2x-3

6, |2x-1|<x+2

7, 3/2-x<=1

8, 2+3x-x^2<=√4+3x-x^2

9, √x^2-5x+6<5-x

10, x^2-6>5(x+√x^2-5x)

11, |x^2-x|<=x^2-x

1, √x^2-5x+8<=3x-10

2, x^2-4x+3/3-2x<1-x

3, |x^2+x-2|+3x^2-3>0

4, |x+3|>=2(1+x^2)

5, |x^2-1|>x^2+2x-3

6, |2x-1|<x+2

7, 3/2-x<=1

8, 2+3x-x^2<=√4+3x-x^2

9, √x^2-5x+6<5-x

10, x^2-6>5(x+√x^2-5x)

11, |x^2-x|<=x^2-x

Tìm x 

a) 3/5 - 2/7 < 2/3*x +3/4 < 1 / 2 + 7/9 

b) 1/6 + 1/9 < 2/3 - 3/4*x < 2/3 + 1.25 

c) 1+ 1/3 + 1 /6 + 1/10 +........+ 2/x.(x+1) = 3992/1997

a,-8/3+7/5+-71/15<x<-13/7+19/14+-7/2

b,-19/6+-15/2+11/3<x<-5/4+19/12+-10/3

c,-6/7+3/35<x<-2/5+3/7

d,x=3/4+1/-12

e,x/14=1/7+-3/14

f,11/18+13/6=85/x

g,8/17+5/17<x/17<6/17+9/17

Tìm các số nguyên x thỏa mãn:

a) -1/4 : -3/4 + 1/2 < x < 7/8 - 1/2 : -5/6

b) (-2/3 - 1/2) : -1/4 < x < ( -5/6 + 9/4 : -3/2 ).(-13/2)