-5/9.13/28-13/28.4/9
Tính tổng sau : S = 2/5*9 +2/9.13+2/13*17+......+2/97*101
Bài 1 : Tìm x biết :
x + 4/5.9 + 4/ 9.13 + 4/ 13 .15 + ... + 4/41.45 = -37/45
Bài 2 : x - 20/11.13 - 20/13.15 - ...-20/53.55= 3/11
Bài 3 : Tìm x biết
1/21 + 1/28 + 1/36 + ...+ 2/ x(x+1)=2/9
-5/9 . 13/28 - 13/28 . 4/9
-5/9 x 13/28 - 13/28 x 4/9
-5/9 . 13/28 - 13/28 . 4/9
= 13/28 . (-5/9 - 4/9)
= 13/28 . (-1)
= -13/28
`-5/9 xx 13/28 - 13/28 xx 4/9`
`= 13/28 xx ((-5)/9 - 4/9)`
`= 13/28 xx (-1)`
`= -13/28`
E=5/9.13+7/9.25+13/19.25+31/19.69
5/9 nhân 13/28 +13/28 nhân4/9
5/9x13/28+13/28x4/9
=(5/9+4/9)x13/28
=1x13/28
=13/28
5/9 x 13/28 +13/28 x 4/9
= 13/28 x ( 5/9 + 4/9 )
= 13/28 x 1
= 13/28
Tính
E= 5/9.13 + 7/9.25 + 13/19.25 + 31/19.69
Tính:
-5/9.13 -7/9.25 - 13 / 9.25 - 31 / 19. 69
(112/13x20)+(112/20x27)+...+(112/62x69):(-5/9.13-7/9x25-13/19x25-31/19x69)