\(A=\dfrac{15}{11.14}+\dfrac{15}{14.17}+...+\dfrac{15}{68.71}\)
\(=5\left(\dfrac{3}{11.14}+\dfrac{3}{14.17}+...+\dfrac{3}{68.71}\right)\)
\(=5\left(\dfrac{1}{11}-\dfrac{1}{14}+\dfrac{1}{14}-\dfrac{1}{17}+...+\dfrac{1}{68}-\dfrac{1}{71}\right)\)
\(=5\left(\dfrac{1}{11}-\dfrac{1}{71}\right)\)
\(=5.\dfrac{60}{781}=\dfrac{300}{781}\)
Vậy...
Tính
A=15/11×14+15/14×17+15/17×20+....+15/68×71
(14,17,20,....,71 la ở trên nhak. Ko có ở mẫu số)
Mk cần gấp nhak
!!!
số nguyên:
15 - ( -15 + 2)=
(-14) - (17 - 8)=
15 - ( 21- 7)=
34 + (-15) - 17=
(-34) + ( -12) + 18=
27 - 15 - 19=
34 - ( -15) +8=
-37 + 13 - 25=
40 - 17 + ( -25)=
16 + (-15 ) - 18=
15 - 14 - 13=
-27 + 15 -17=
34 - 71=
28 - 125=
13 + ( -27)=
14 - (-34)=
28 - (-16)=
-15 -8 =
-27 -34=
-25 - (-18)=
46 - 25 - (-25)=
-37 - (-24)=
46 - (-15)=
-26 - 6 + 7 =
Bài 1:Tính bằng cách hợp lý
a,\(^{6^{12}}\).15+\(^{6^{12}}\).19-\(^{6^{12}}\).34
b.\(^{^{ }}4^{^{ }15}\).37+\(^{^{ }}4^{^{ }15}\).23-\(^{^{ }4^{14}}\).240
c.\(^{^{ }5^{17}}\).125-\(^{^{ }5^{18}}\).25+\(^{^{ }6^3}\):8
Bài 2:Tìm n biết
a.143+7.(n-17)=206
b.128-28:(15-n)=124
c.\(^{^{ }3_{ }^n}\).2+48=210
Lưu ý:Dấu . là nhân nha
Giúp mk mau nha m.n mk cần gấp lắm ai đúng mk tick cho
số nguyên:
15 - ( -15 + 2)=
(-14) - (17 - 8)=
15 - ( 21- 7)=
34 + (-15) - 17=
(-34) + ( -12) + 18=
27 - 15 - 19=
34 - ( -15) +8=
-37 + 13 - 25=
40 - 17 + ( -25)=
16 + (-15 ) - 18=
15 - 14 - 13=
-27 + 15 -17=
34 - 71=
28 - 125=
13 + ( -27)=
14 - (-34)=
28 - (-16)=
-15 -8 =
-27 -34=
-25 - (-18)=
46 - 25 - (-25)=
-37 - (-24)=
46 - (-15)=
-26 - 6 + 7 =
A = 15/14 + 16/15 + 17/16 + 18/17
SO SÁNH A VỚI 4
B = 2015/2016 + 2016/2017 + 2016/2019
SO SÁNH B VỚI 3
bỏ dấu ngoặc rồi tính:
a) (15+37) +(52-37-17)
b) ( 38-42+14)-(25-27-15)
c)( 21 - 32 ) -( - 12 + 32 )
d)-(12 + 21 -23)-(23-21)
tính
\(\dfrac{-5}{8}:\dfrac{15}{4}\) \(\dfrac{-15}{17}:\dfrac{25}{-34}\) \(-48:(\dfrac{-24}{5})\) \(\dfrac{-30}{7}:(\dfrac{-5}{-14})\)
\(\dfrac{15}{28}:(\dfrac{-9}{14})\) \(\dfrac{-7}{40}:(-\dfrac{21}{20})\) \((\dfrac{-4}{15}).(-\dfrac{-25}{8})\) \(\dfrac{5}{-14}.(-\dfrac{7}{10})\)
\(\dfrac{-15}{4}.(-\dfrac{16}{25})\) \(15.(-\dfrac{13}{10})\) \((-\dfrac{14}{5}).-10\) \((\dfrac{3}{-10}).(-\dfrac{-15}{2})\)
Bài 1: Tìm x , biết:
1) x - 2 = -6 12) 3 . | x - 1 | - 5 = 7
2) -5 . x - ( -3 ) = 13 13) -12 . ( x - 5 ) + 7 . ( 3 - x ) = 5
3) 15 - ( x - 7 ) = -21 14) ( x - 2 ) . ( x + 4 ) = 0
4) 3 .x + 17 = 2 15) ( x - 2 ) . ( x + 15 ) = 0
5) 45 - ( x - 9 ) = -35 16) ( 7 - x ) . ( x + 19 ) = 0
6) ( -5 ) + x = 15 17) -5 < x < 1
7) 2 . x - ( -17 ) = 15 18) | x | < 3
8) | x - 2 | = 3 19) ( x - 3 ) . ( x - 5 ) < 0
9) | x - 3 | - 7 = 13 20) 2 . x2 - 3 = 29
10) 72 - 3 . | x + 1 | = 9 21) -6 . x - ( -7) = 25
11) 17 - ( 43 - | x | ) = 45 22) 46 =- ( x - 11 ) = -48
Bai 1 : Tinh a) 24 - (-15) - 2 b) (-85) + 10 - (-85) - 50 c) 71 - (-30) - (+18) + (-30)
d) -(30) - (+37) + (+37) + (-85) e) (35-815) - (795-65) g) (2002-79+15) + (-79+15)
h) -(515-80+91) - (2003+80-91)
Bai 2: Tim x,biet a) 25 - (30+x) = x - (27-8) b) (x-12) - 15 = (20-17) - (18+x) c) 15 - x = 7 - (-2) d) x - 35 = (-12) - 3 e) I5-xI - 26 = - 15
