9/5:17/15+8/5:17/15

=(9/5+8/5):17/15

=17/5:17/15

=3

Chúc bạn học giỏi nha!!!

K cho mik vs nhé Tuyên

9/5:17/15+8/5+17/15

=(9/5+8/5):17/15

=17/5:17/15

=3

la 3 day

15315300                                          

:2*3*5*7*11*13*15*17*2=15315300

tìm vô mạng đc  mà

=-17/15-9/17-2/3+9/17

=-17/15-10/15

=-27/15

=-9/5

Giải:

\(\left(\dfrac{-17}{15}-\dfrac{9}{17}\right)-\left(\dfrac{2}{3}-\dfrac{9}{17}\right)\)

⇔ \(\dfrac{-17}{15}-\dfrac{9}{17}-\dfrac{2}{3}+\dfrac{9}{17}\)

⇔\(\dfrac{-17}{15}-\dfrac{10}{15}\)

\(\Leftrightarrow\dfrac{-27}{15}=\dfrac{-9}{5}\)

=-17/15-9/17-2/3+9/17

=-17/15-10/15

=-27/15

=-9/5

a) 3/7 + 4/9 + 4/7 + 5/9

= ( 3/7 + 4/7 ) + ( 4/9 + 5/9 )

= 7/7 + 9/9

= 1  + 1 

= 2

b)1/5 + 4/10 + 9/15 + 16/20 + 25/25 + 36/30 + 49/35 + 64/40 + 81/45

= 1/5 + 2/5 + 3/5 + 4/5 + 5/5 + 6/5 + 7/5 + 8/5 + 9/5

= ( 1/5 + 9/5 ) + ( 2/5 + 8/5 ) + (7/5 + 3/5 ) + ( 4/5 + 6/5  ) + 5/5

= 2 + 2 + 2 + 2 + 1

= 2  x 4 + 1

= 8  +1 

= 9

c)  1/8 + 1/12 + 3/8 + 5/12

= ( 1/8 + 3/8 ) + ( 1/12 + 5/12)

= 4/8 + 6/12

= 1/2 + 1/2

= 2/4 = 1/2

mỏi tay rồi

d; (1 - \(\dfrac{1}{2}\)) x (1 - \(\dfrac{1}{3}\)) x (1 - \(\dfrac{1}{4}\)) x ... x ( 1 - \(\dfrac{1}{100}\))

 = \(\dfrac{1}{2}\) x \(\dfrac{2}{3}\)  x \(\dfrac{3}{4}\) x \(\dfrac{3}{4}\) x ... x \(\dfrac{99}{100}\)

= \(\dfrac{1}{100}\)

e; \(\dfrac{9}{5}\) : \(\dfrac{17}{15}\) + \(\dfrac{8}{5}\) : \(\dfrac{17}{15}\)

=  \(\dfrac{9}{5}\) x \(\dfrac{15}{17}\) + \(\dfrac{8}{5}\) x \(\dfrac{15}{17}\)

=  \(\dfrac{27}{17}\) + \(\dfrac{24}{17}\)

=  \(\dfrac{51}{17}\)

=   3

(2¹⁷ + 17²).(9¹⁵ - 3¹⁵).(2⁴ - 4²)

= (2¹⁷ + 17²).(9¹⁵ - 3¹⁵).(16 - 16)

= (2¹⁷ + 17²).(9¹⁵ - 3¹⁵).0

= 0

  (217 + 172) (915 - 315) (24 - 42)
= (217 + 172).(915 - 315).(16 - 16)
= (217 + 172).(915 - 315).0 = 0
 

_{khum bt}

10 < 10 + 3

11 + 2=2 + 11

9 < 10 + 9

10 = 10 + 0

17 – 4 > 14 - 3

18 – 4 >12

15 > 15 – 1

17 + 1<17 + 2

12+ 5 > 16

16 =19 - 3

15 – 4 =10 + 1

19 – 3 >11

Đặt A = 1.3 + 3.5 + 5.7  + ... + 15.17 + 17.19 

6A = 1.3.6 + 3.5.6 + .... + 15.17.6 + 17.19.6 

6A = 1.3.(5 + 1) + 3.5.(7 - 1) + ... + 15.17.(19 - 13) + 17.19.(21 - 15)

6A = 1.3.5 + 1.3 + 3.5.7 - 1.3.5 + ... + 15.17.19 - 13.15.17 + 17.19.21 - 15.17.19

6A = (1.3.5 + 3.5.7 + ... + 15.17.19 + 17.19.21) - ( 1.3.5 + ... + 13.15.17 + 15.17.19) + 1.3

6A = 17.19.21 + 1.3

6A = 6783 + 3 

6A = 6786

A = 6780 : 6 = 1131