36*2+36*5+3*36
Tính nhanh:
36*2+36*5+3*36=...........................
36 x 2 + 36 x 5 + 36 x 3
= 36 x ( 2 + 3 + 5 )
= 36 x 10
= 360
36/(1*3*5) + 36/(3*5*7) + 36/(5*7*9) + ... + 36/(25*27*29)
CTR:36/1*3*5+36/3*5*7+36/5*7*9+...+36/25*27*29<3
Tính tổng: A=36/(1*3*5)+36/(3*5*7)+36/(5*7*9)+...+36/(45*47*49)
a) 16 . 36 - 16 . 37
b) 36 : 4 . 3 + 9 . 50
c) 2 . (5 . 16 - 18) + 36 : 18 . 2
d) 48 : 8 . 5 + 5 . 44
e) 5 . 4 - 18 : 3
f) 2 . 25 + 169 : 13 - 54 : 27
a) \(...=16.\left(36-37\right)=16.\left(-1\right)=-16\)
b) \(...=9.3+9.50=9.\left(3+50\right)=9.53=477\)
c) \(...=2.\left(\left(5.16-18\right)+36:18\right)=2.\left(70+2\right)=2.72=144\)
d) \(...=5\left(48:8+44\right)=5\left(6+44\right)=5.50=250\)
e) \(...=20-6=14\)
f) \(...=50+13-2=61\)
Cô tick xanh cho bạn Đức Trí, các câu khác em làm theo bạn vì bạn làm đúng còn câu c em làm theo cô nhé.
Câu c,
2.(5.16 - 18) + 36:18.2
= 2.(80 - 18) + 2.2
= 2.62 + 4
= 128
d) 48 : 8 . 5 + 5 . 44
= 6 . 5 + 5 . 44
= 5 . (6 + 44)
= 5 . 50
= 250
e) 5 . 4 - 18 : 3
= 20 - 6
= 14
f) 2 . 25 + 169 : 13 - 54 : 27
= 50 + 13 - 2
= 61
Hoàn thành các phép tính sau :
7/9+5/12-3/4=7×4/36+5×.../36-3×.../36
=28+..._.../36
=16/36=.../...
E = 36 / 1.7 + 36 / 7.13 + 36 / 13.19 + .... + 36 / 94.100
F = 1 / 10 + 1 / 40 + 1 / 88 + .... + 1 / ( 3a+z) ( 3a+ 5)
G = 1 / 2.3 + 2 / 3.5 + 3 / 5.8 + 4 / 8.12 + 5 / 12.17
E = \(\frac{36}{1\cdot7}+\frac{36}{7\cdot13}+...+\frac{36}{94\cdot100}=\frac{36}{6}\left[\frac{1}{1\cdot7}+\frac{1}{7\cdot13}+...+\frac{1}{94\cdot100}\right]\)
\(=6\left[1-\frac{1}{7}+\frac{1}{7}-\frac{1}{13}+...+\frac{1}{94}-\frac{1}{100}\right]=6\left[1-\frac{1}{100}\right]\)
\(=6\cdot\frac{99}{100}=\frac{297}{50}\)
F = \(\frac{1}{10}+\frac{1}{40}+\frac{1}{88}+...+\frac{1}{\left[3a+2\right]\left[3a+5\right]}\)
\(=\frac{1}{2\cdot5}+\frac{1}{5\cdot8}+\frac{1}{8\cdot11}+...+\frac{1}{\left[3a+2\right]\left[3a+5\right]}\)
\(=\frac{1}{3}\left[\frac{1}{2}-\frac{1}{5}+\frac{1}{5}-\frac{1}{8}+\frac{1}{8}-\frac{1}{11}+...+\frac{1}{3a+2}-\frac{1}{3a+5}\right]\)
\(=\frac{1}{3}\left[\frac{1}{2}-\frac{1}{3a+5}\right]=\frac{1}{6}-\frac{1}{9a+15}\)
G = \(\frac{1}{2\cdot3}+\frac{2}{3\cdot5}+\frac{3}{5\cdot8}+\frac{4}{8\cdot12}+\frac{5}{12\cdot17}=\frac{1}{2}-\frac{1}{3}+\frac{1}{3}-\frac{1}{5}+...+\frac{1}{12}-\frac{1}{17}\)
\(=\frac{1}{2}-\frac{1}{17}=\frac{15}{34}\)
E=36/1-36/7+36/7-36/13+...+36/94-36/100
=36-36/100=891/25
tính hợp lí
a 36*105-36*5
b 2*169*12-3*68-24
c 2*56*24-3*36*16+4*12*95-6*3*8*5
a) 36.105-36.5
= 36(105-5)
=36.100
= 3600
tíc mình nha
chứng minh B = 36 / 1 x 3 x 5 + 36 / 3 x 5 x7 + 36 / 5 x 7 x 9 + .... + 36 / 25 x 27 x29 < 3
\(B=\frac{36}{1.3.5}+\frac{36}{3.5.7}+\frac{36}{5.7.9}+...+\frac{36}{25.27.29}\)
\(=9.\left(\frac{4}{1.3.5}+\frac{4}{3.5.7}+\frac{4}{5.7.9}+...+\frac{4}{25.27.29}\right)\)
\(=9.\left(\frac{1}{1.3}-\frac{1}{3.5}+\frac{1}{3.5}-\frac{1}{5.7}+\frac{1}{5.7}-\frac{1}{7.9}+...+\frac{1}{25.27}-\frac{1}{27.29}\right)\)
\(=9.\left(\frac{1}{3}-\frac{1}{675}\right)\)
\(=9.\frac{224}{675}\)
\(=\frac{224}{75}\)
THIẾU
\(=\frac{224}{75}< \frac{225}{75}=3\)
Vậy \(B< 3\)
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