bài 1 tính

a) (3/7+-9/8)+(5/8+-6/14)

b) (-5/7+3/11)+(-11/14+14/-11)

c)(-4/5+2/3)+(-5/4+19/5)+(7/3.2)

d)9/16.13/4-9/4.5/16+9/16.17/4

(-5) + (-7) + (-8) + (-3) =

(-4)+((-2)+(-5)+(-6)=

(-8)+(-11)+(-4)+(-2)=

(-9)+((-15)+(-6)+(-3)=

(-12)+(-9)+(-3)+(-8)=

(+3)+(+11)+(+14)+(+7)=

(+9)+(+5)+(+14)+(+2)=

(+12)+(+10)+(+3)+(+5)=

(+4)+(+7)+(+12)+(+15)=

(+20)+(+14)+(+3)+(+7)=

ai lam minh tick cho

4 [-2(8:4)+15(-3)-(-12)

3(25:5-14:2)-5(6:2)

[-15:(-3)]-3[2(5-9):3]

-16:(-4)[7-2(15:3)]

-7[8-3(14:7)-12:(-4)]-3(-2)

2[3-9:(-3)+2(5-7)]-18:(-9)

-16:(-8)+5[3-15:5+2] (-3+4)

4[-2(8:4)+15:(-3)-(-12)

3(25:5-14:2)-5(6:2)

[-15:(-3)]-3[2(5-9):3)]

-16:(-4)[7-2(15:3)]

-7[8-3(14:7)-12:(-4)]-3(-2)

2[3-9:(-3)+2(5-7)]-18:(-9)

-16:(-8)+5[3-15:5+2] (-3+4)

Tính:

a) \(\dfrac{1}{7}+\dfrac{2}{7}+\dfrac{3}{7}\)                               b) \(\dfrac{2}{9}+\dfrac{5}{9}+\dfrac{8}{9}\)

c) \(\dfrac{13}{14}-\dfrac{5}{14}-\dfrac{1}{14}\)                          d) \(\dfrac{7}{11}-\dfrac{4}{11}-\dfrac{3}{11}\)

4)(3 1/2 + 2x) : 3/14 = 7/12
5)1/4 + 1/3 : (3x) = -5
6)2 7/9 - 3/4 (x+1) = 7/9

1/2+2/3+3/4+4/5+5/6+6/7+7/8+8/9+9/10+10/11+11/12+12/13+13/14+14/15=?