Tính: A= (1 - 3/8) x(1 - 3/15) x (1 - 3/24) x ... x (1 - 3/143)
Những câu hỏi liên quan
Tính K=(1-3/8)x(1-3/15)x(1-3/24)...x(1-3/399)
\(K=\left(1-\dfrac{3}{2\cdot4}\right)\left(1-\dfrac{3}{3\cdot5}\right)\cdot...\cdot\left(1-\dfrac{3}{19\cdot21}\right)\)
\(=\dfrac{3^2-1-3}{\left(3-1\right)\left(3+1\right)}\cdot\dfrac{4^2-1-3}{\left(4-1\right)\left(4+1\right)}\cdot...\cdot\dfrac{20^2-4}{\left(20-1\right)\left(20+1\right)}\)
\(=\dfrac{\left(3-2\right)\left(3+2\right)}{\left(3-1\right)\left(3+1\right)}\cdot\dfrac{\left(4-2\right)\left(4+2\right)}{\left(4-1\right)\left(4+1\right)}\cdot...\cdot\dfrac{18\cdot22}{\left(20-1\right)\left(20+1\right)}\)
\(=\dfrac{1\cdot5}{2\cdot4}\cdot\dfrac{2\cdot6}{3\cdot5}\cdot...\cdot\dfrac{18\cdot22}{19\cdot21}\)
\(=\dfrac{1\cdot2\cdot3\cdot...\cdot21\cdot22}{2\cdot3\cdot4\cdot5\cdot...\cdot19\cdot20\cdot21}=1\cdot22=22\)
Đúng 1
Bình luận (0)
Xin các anh các chị giải dùm e ạ e xin cảm ơn nhìu 1. TÍNH a) 5/7 × 5/11 + 5/7 × 211 - 5/7 × 14/14 b) 20/9 ÷ 10/9 - 46/5 ÷ 23/5c) 28/15 × (0,5)^2 × 3 + (8/15 + 79/60) ÷ 47/24d) 1/15 + 1/35 + 1/63 + 1/99 + 1/143 + 1/1952. TÌM Xa) 3/2 + x 3/2 -7b) 4/5x 8/35 ÷ 4/7c) 3/5x -1/21/7d) 1-( 43/8 + x - 36/24) ÷ (-46/3)03. Tìm x thuộc z sau cho 2x+1/x-3 cũng là số tự nhiên Máy a máy chị làm dc câu nào làm dùm e nha
Đọc tiếp
Xin các anh các chị giải dùm e ạ e xin cảm ơn nhìu
1. TÍNH
a) 5/7 × 5/11 + 5/7 × 211 - 5/7 × 14/14
b) 20/9 ÷ 10/9 - 46/5 ÷ 23/5
c) 28/15 × (0,5)^2 × 3 + (8/15 + 79/60) ÷ 47/24
d) 1/15 + 1/35 + 1/63 + 1/99 + 1/143 + 1/195
2. TÌM X
a) 3/2 + x = 3/2 -7
b) 4/5x = 8/35 ÷ 4/7
c) 3/5x -1/2=1/7
d) 1-( 43/8 + x - 36/24) ÷ (-46/3)=0
3. Tìm x thuộc z sau cho 2x+1/x-3 cũng là số tự nhiên
Máy a máy chị làm dc câu nào làm dùm e nha
Ko mìk ko đi chơi bạn giải dc câu nào ko giải giúp mìk vs
Đúng 0
Bình luận (0)
1.Tìm các số nguyên x:
5/17+-4/9+-20/31+12/17+-11/31<x<=-3/7+7/15+4/-7+8/15+2/3
2. Tính
A=5-10/19+15/143-5/81+8-16/26+24/243-8/181
6-12/19+18/143-6/81+9-18/26+27/243-9/181
Bài 5: Tính bằng cách thuận tiện nhất ; câu b tất cả là hỗn số a) 2/3 : 3/5 x 5/7 : 2/3 + 2023 b) 1,1/2 x 1, 1/3 x 1, 1/8 x 1,1/15 x 1, 1/24 x 1, 1/35
Đọc tiếp
Bài 5: Tính bằng cách thuận tiện nhất ; câu b tất cả là hỗn số
a) 2/3 : 3/5 x 5/7 : 2/3 + 2023 b) 1,1/2 x 1, 1/3 x 1, 1/8 x 1,1/15 x 1, 1/24 x 1, 1/35
a) 2/3 : 3/5 × 5/7 : 2/3
= 2/3 × 5/3 × 5/7 × 3/2
= 25/21
b) 1 1/2 × 1 1/3 × 1 1/18 × 1 1/15 × 1 1/24 × 1 1/35
= 3/2 × 4/3 × 19/18 × 16/15 × 25/24 × 36/35
= 2 × 152/35 × 15/14
= 304/35 × 15/14
= 152/7
Đúng 2
Bình luận (0)
Bài 1: Tính nhanh
a) 1 x 3 + 2 x 4 + 3 x 5 + 4 x 6 + ..... + 99 x 100
b) 8/9 x 15/16 x 24/25 x ... x 2499/2500
Xem chi tiết
a,0,25.1+3/5.(5/4)2:4/7
b,1/15+1/35+1/63+1/99+1/143+1/195
c,1-(5+3/8+x-7+5/24):(-16+2/3)=0
Tính nhanh theo mẫu:
Mẫu: Bleft(1+dfrac{1}{3}right)x left(1+dfrac{1}{8}right)x left(1+dfrac{1}{15}right)x left(1+dfrac{1}{24}right)x ..... x left(1+dfrac{1}{120}right)x left(1+dfrac{1}{413}right)
Bleft(dfrac{3}{3}+dfrac{1}{3}right)x left(dfrac{8}{8}+dfrac{1}{8}right)x left(dfrac{15}{15}+dfrac{1}{15}right)x left(dfrac{24}{24}+dfrac{1}{24}right)x........xleft(dfrac{120}{120}+dfrac{1}{120}right)x left(dfrac{143}{143}+dfrac{1}{143}right)
Bdfrac{4}{3}xdfrac{9}{8}xdfrac{16}{15}xdfrac{25}{24}x.........
Đọc tiếp
Tính nhanh theo mẫu:
Mẫu: \(B=\left(1+\dfrac{1}{3}\right)\)x \(\left(1+\dfrac{1}{8}\right)\)x \(\left(1+\dfrac{1}{15}\right)\)x \(\left(1+\dfrac{1}{24}\right)\)x ..... x \(\left(1+\dfrac{1}{120}\right)\)x \(\left(1+\dfrac{1}{413}\right)\)
\(B=\left(\dfrac{3}{3}+\dfrac{1}{3}\right)\)x \(\left(\dfrac{8}{8}+\dfrac{1}{8}\right)\)x \(\left(\dfrac{15}{15}+\dfrac{1}{15}\right)\)x \(\left(\dfrac{24}{24}+\dfrac{1}{24}\right)\)x........x\(\left(\dfrac{120}{120}+\dfrac{1}{120}\right)\)x \(\left(\dfrac{143}{143}+\dfrac{1}{143}\right)\)
\(B=\dfrac{4}{3}\)x\(\dfrac{9}{8}\)x\(\dfrac{16}{15}\)x\(\dfrac{25}{24}\)x.......x\(\dfrac{121}{120}\)x \(\dfrac{144}{143}\)
\(B=\dfrac{2x2}{1x3}\)x\(\dfrac{3x3}{2x4}\)x\(\dfrac{4x4}{3x5}\)x\(\dfrac{5x5}{4x6}\)x.......x\(\dfrac{11x11}{10x12}\)x\(\dfrac{12x12}{13x11}\)
\(B=\dfrac{2x3x4x5x......x10x11x12}{1x2x3x......x10x11x12}\)x \(\dfrac{2x3x4x5x....x11x12}{3x4x5x6x......x12x13}\)
B= \(\dfrac{12}{1}\)x\(\dfrac{2}{13}\)
B=\(\dfrac{24}{13}\)
Câu hỏi:
\(B=\left(1+\dfrac{1}{8}\right)\)x\(\left(1+\dfrac{1}{15}\right)\)x\(\left(1+\dfrac{1}{24}\right)\)x..... x \(\left(1+\dfrac{1}{440}\right)\)x \(\left(1+\dfrac{1}{483}\right)\)
\(B=\left(1+\dfrac{1}{8}\right)\left(1+\dfrac{1}{15}\right)\left(1+\dfrac{1}{24}\right).....\left(1+\dfrac{1}{440}\right)\left(1+\dfrac{1}{483}\right)\)
\(B=\dfrac{9}{8}.\dfrac{16}{15}.\dfrac{25}{24}.....\dfrac{441}{440}.\dfrac{484}{483}\)
\(B=\dfrac{9.16.25.....441.484}{8.15.24.....440.483}\)
\(B=\dfrac{3.3.4.4.5.5.....21.21.22.22}{2.4.3.5.4.6.....20.22.21.23}\)
\(B=\dfrac{3.4.5.....21.22}{2.3.4.....20.21}.\dfrac{3.4.5.....21.22}{4.5.6.....22.23}\)
\(B=11.\dfrac{3}{23}=\dfrac{33}{23}\)
Đúng 0
Bình luận (0)
B = \(\dfrac{4}{3}.\dfrac{9}{8}.\dfrac{16}{15}.\dfrac{25}{24}...\dfrac{121}{120}.\dfrac{144}{143}\)
B = \(\dfrac{4.9.16.25...121.144}{3.8.15.24....120.143}\)
B = \(\dfrac{2.2.3.3.4.4.5.5...11.11.12.12}{1.3.2.4.3.5.4.6...10.12.11.13}\)
B = \(\dfrac{2.3.4.5...11.12}{1.2.3.4.5...10.11}.\dfrac{2.3.4.5...11.12}{3.4.5.6.7...12.13}\)
B = 12 . \(\dfrac{2}{13}\)
B = \(\dfrac{24}{13}\)
Đúng 0
Bình luận (2)
1) so sánh phân số
a) -8/12 và -3/-4 b)-56 /24 và 7/3 c) -4/25 và 15/-13
2) tính
a) 3/5 x 20/ -9
b)4/15 + -3/2 +8/-5
c) 19/35 x -38/7
d) -7/12 x 13/14 +1/14 x (-7) /12
Bài 1:
a: -8/12<0<-3/-4
b: -56/24<0<7/3
c: 4/25<1<15/13
=>-4/25>-15/13
Bài 2:
a: =-60/45=-4/3
b: =4/15-3/2-8/5=8/30-45/30-48/30=-85/30=-17/6
Đúng 0
Bình luận (0)
1. tinh :
a) 15/8 + 3/4 - 5/12
b) 11/24 x 12/33 + 5/6
c) 15/8 + 7/24 : 5/8
2 . tim x, biet :
a) x + 5/8 : 3/4 = 17/9
b) x - 5/9 x 18/15 = 1/3
c) x x7/8 - 5/8 = 13/24
d) X x1/7 + X x 1/4 + X x 1/4 =18
giup mik nhanh nha. mik can gap lam
a)15/8+3/4-5/12
=45+18-10/24
=53/24
b)11/24.12/33+5/6
=11.12/12.2.11.3+5/6
=1/6+5/6
=6/6=1
c)15/8+7/24:5/8
=15/8+7/24.8/5
=15/8+7.8/3.8.5
=15/8+7/15
=đề sai, nếu đúng thì như này
=8/15+7/15
=15/15=1
Đúng 0
Bình luận (0)
