\(\frac{755}{4562}+\frac{?}{?}=1\)
Tính tổng :
\(\frac{1}{7}+\frac{1}{91}+\frac{1}{247}+\frac{1}{475}+\frac{1}{755}+\frac{1}{1147}\)
\(\frac{1}{7}+\frac{1}{91}+\frac{1}{247}+\frac{1}{475}+\frac{1}{755}+\frac{1}{1147}\)
\(=\frac{1}{7}+\frac{1}{7.13}+\frac{1}{13.19}+\frac{1}{19.25}+\frac{1}{25.31}+\frac{1}{31.37}\)
\(=\frac{1}{6}\left(1-\frac{1}{37}\right)\)
\(=\frac{1}{6}.\frac{36}{37}\)
\(=\frac{6}{37}\)
\(\frac{1}{7}+\frac{1}{91}+\frac{1}{247}+\frac{1}{475}+\frac{1}{755}+\frac{1}{1147}\)
\(=\frac{1}{1.7}+\frac{1}{7.13}+\frac{1}{13.19}+\frac{1}{19.25}+\frac{1}{25.31}+\frac{1}{31.37}\)
\(=\frac{1}{6}.\left(\frac{6}{1.7}+\frac{6}{7.13}+\frac{6}{13.19}+\frac{6}{19.25}+\frac{6}{25.31}+\frac{6}{35.37}\right)\)
\(=\frac{1}{6}.\left(1-\frac{1}{7}+\frac{1}{7}-\frac{1}{13}+\frac{1}{13}-\frac{1}{19}+\frac{1}{19}-\frac{1}{25}+\frac{1}{25}-\frac{1}{31}+\frac{1}{31}-\frac{1}{37}\right)\)
\(=\frac{1}{6}.\left(1-\frac{1}{37}\right)\)
\(=\frac{1}{6}.\frac{36}{37}=\frac{6}{37}\)
~ Hok tốt ~
\(\frac{1}{6}\left(\frac{6}{7}+\frac{6}{91}+\frac{6}{247}+\frac{6}{475}+\frac{6}{755}+\frac{6}{1147}\right)\)
\(=\frac{1}{6}\left(\frac{6}{1\cdot7}+\frac{6}{7\cdot13}+\frac{6}{13\cdot19}+\frac{6}{19\cdot25}+\frac{6}{25\cdot31}+\frac{6}{31\cdot37}\right)\)
\(=\frac{1}{6}\left(1-\frac{1}{7}+\frac{1}{7}-\frac{1}{13}+\frac{1}{13}-\frac{1}{19}+\frac{1}{19}-\frac{1}{25}+\frac{1}{25}-\frac{1}{31}+\frac{1}{31}-\frac{1}{37}\right)\)
\(=\frac{1}{6}\left(1-\frac{1}{37}\right)\)
\(\frac{1}{6}\left(\frac{37}{37}-\frac{1}{37}\right)=\frac{1}{6}\cdot\frac{36}{37}=\frac{1\cdot6\cdot6}{6\cdot37}=\frac{6}{37}\)
CMR:
A) \(\frac{113}{342}>\frac{251}{755}\) VÀ
B)\(\frac{1784}{3456}>\frac{673}{1234}\) là ko đúng
1. Tính
K = \(\frac{1}{7}\)+\(\frac{1}{91}\)+\(\frac{1}{247}\)+\(\frac{1}{475}\)+\(\frac{1}{755}\)+\(\frac{1}{1147}\)
2. Chứng minh rằng
\(\frac{1}{4}\)+\(\frac{1}{16}\)+\(\frac{1}{36}\)+\(\frac{1}{64}\)+\(\frac{1}{100}\)+\(\frac{1}{144}\)+\(\frac{1}{196}\)<\(\frac{1}{2}\)
Ta có:
\(K=\frac{1}{7}+\frac{1}{91}+\frac{1}{247}+\frac{1}{475}+\frac{1}{775}+\frac{1}{1147}\)
\(=\frac{1}{1.7}+\frac{1}{7.13}+\frac{1}{13.19}+\frac{1}{19.25}+\frac{1}{25.31}+\frac{1}{31.37}\)
\(=\frac{1}{6}\left(1-\frac{1}{7}+\frac{1}{7}-\frac{1}{13}+\frac{1}{13}-\frac{1}{19}+\frac{1}{19}-\frac{1}{25}+\frac{1}{25}-\frac{1}{31}+\frac{1}{31}-\frac{1}{37}\right)\)
\(=\frac{1}{6}.\left(1-\frac{1}{37}\right)=\frac{1}{6}.\frac{36}{37}=\frac{6}{37}\)
K = \(\frac{1}{7}+\frac{1}{91}+\frac{1}{247}+\frac{1}{475}+\frac{1}{755}+\frac{1}{1147}=0,1621963429\)
Không thực hiện phép tính, hãy so sánh các biểu thức sau: a) |234 + 345| và |234| + |345|; b) |(-3567) + (-4562)| và |-3567| + |-4562|; c) |23 + (-2)| và |23| + |-2|.
15×32+8907-4562÷8764=........?
Bài 1 : Tính Giá Trị Biểu Thức
4562 + 234 x 9 45235 : 5 + 4587
( 4587 - 587 ) x 45 789 x 6 - 987
4562 + 234 x 9
= 4562 + 2106
= 6668
45235 : 5 + 4587
= 9047 + 4587
= 13634
( 4587 - 587 ) x 45
= 4000 x 45
= 180 000
789 x 6 - 987
= 4734 - 987
= 3747
\(4562+234\times9\)
\(=4562+2106\)
\(=6668\)
__________________________
\(45235:5+4587\)
\(=9047+4587\)
\(=13634\)
__________________________
\(\left(4587-587\right)\times45\)
\(=4000\times45\)
\(=180000\)
__________________________
\(789\times6-987\)
\(=4734-987\)
\(=3747\)
Tính nhanh
4562+-4400+234+-162
Tính bằng cách thuận tiện nhất :
456 × 4 + 456 × 3 + 4562
456*4+456*3+4562
=456*(4+3)+4562
=456*7+4562
=3192+4562
=7754
x+120=453
4562+x=6336
ai nhanh mk tk
x+120=453 4562+x=6336
x =453-120 x=6336-4562
x = 333 x = 1774
~chúc bn hok tốt~
x+120=453 suy ra x= 453-120= 333.
4562+x=6336 suy ra x= 6336-4562= 1774.