Tính nhanh :
1 + 7 + 8 + 15 + 23 + ... + 160
1 + 4 + 5 + 9 + 14 + ... + 60 + 97
78 x 31 + 78 x 24 + 78 x 17 + 72 x 22
A = 1 x 4 + 2 x 5 + 3 x 6 + 4 x 7 + .... n x ( n+ 3 )
Giúp mình nha,ai làm chi tiết và đúng mình tích 15 cái
Bài 1: Tính
a, 16/15. -5/4. 54/24. 56/21
b, -5/8 . -12/29 . 8/-10 . 29/5
Bài 2: Tính nhanh giá trị của các biểu thức sau:
a, 4.11 . 3/4 . 9/121
b, -7/25 . 39/ -17 . 50/78
c, 3/7. 2/5 . 7/3. 20 . 19/42
Tính hợp lí nếu có thể :
56 : 54 + 23. 22 -225 : 152
7/19 . 8/113/11 .7/19 . -12/19
-7/25 . 39/ 14 . 50/78
(3/8 +-3/4 +7/12):5/6+1/2
2/5.1/3-2/15:1/5+3/5.1/3
\(\dfrac{-5}{9}+1\dfrac{5}{9}\cdot\left(\dfrac{3}{4}-\dfrac{2}{5}\right):7^2\)
\(1\dfrac{13}{15}\cdot0,75-\left(\dfrac{104}{195}+25\%\right)\cdot\dfrac{24}{47}-3\dfrac{12}{13}:3\)
\(1\dfrac{13}{15}\cdot\left(0,5\right)^2\cdot3+\left(\dfrac{8}{15}+1\dfrac{19}{60}\right):1\dfrac{23}{24}\)
tính hợp lý giá trị các biểu thức sau :
A= \(49\frac{8}{23}-\left(5\frac{7}{32}+14\frac{8}{23}\right)\)
B= \(71\frac{38}{45}-\left(43\frac{8}{45}-1\frac{17}{57}\right)\)
C= \(\frac{-3}{7}.\frac{5}{9}+\frac{4}{9}.\frac{-3}{7}+2\frac{3}{7}\)
D = \(\left(19\frac{5}{8}:\frac{7}{12}-13\frac{1}{4}:\frac{7}{12}\right).\frac{4}{5}\)
E= \(0,7.2\frac{2}{3}.20.0,375.\frac{5}{28}\)
F= \(\left(9,75.21\frac{3}{7}+\frac{39}{4}.18\frac{4}{7}\right).\frac{15}{78}\)
a) \(E=\frac{1}{1.2.3}+\frac{1}{2.3.4}+...+\frac{1}{48.49.50}\)
b) \(F=\frac{5.4^{15}.9^9-4.3^{20}.8^9}{5.2^9.6^{19}-7.2^{29}.27^6}\)
c) \(G=\frac{636363.37-373737.63}{1+2+3+...+2017}\)
d) \(H=\left(\frac{12+\frac{12}{19}-\frac{12}{37}-\frac{12}{53}}{3+\frac{1}{3}-\frac{3}{37}-\frac{3}{53}}:\frac{4+\frac{4}{17}+\frac{4}{19}+\frac{4}{2016}}{5+\frac{5}{17}+\frac{5}{19}+\frac{5}{3016}}\right).\frac{124242423}{237373735}\)
giúp mk với ! Help me!
Tính
1) (- 2) . (- 7) . (- 5) 2) 15 – 22 + ( - 17)
3) 25. (- 4) – 20. (- 5) 4) 185 – (49 + 185)
5) ( -19 ) . (- 13) + 13 . (-29)
6)79 . 23 + 21 . 23 7) 2. ( 6 . 42 – 85 : 5)
8) (-5) .8 . (-2) . 3 9) 200 +32 –( 50 +32 )
10) 3 . (-2)2 + 4 . (-5) +20
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
1 . Tính nhanh
a/ 15 . ( 27 + 18 + 6 ) + 15 . ( 23 + 12 )
b/ 14 . 35 . 5 + 10 . 25 .7 + 20 . 70
c/ 53 . ( 51 + 4 ) + 53 . ( 49 + 96 ) + 53
d/ 46 . ( 27 + 75 ) + 8 . ( 58 + 25 ) . 2
