Bài 2: Tính
a) \(\dfrac{30\times25\times7\times8}{75\times8\times12\times14}\)
b)\(\dfrac{8\times3\times4}{16\times3}\)
c)\(\dfrac{4\times5\times6}{3\times10\times8}\)
(Các bạn tách các số ra rồi gạch, gạch xong thì nhân lại và ra kết quả) Thanks
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1 tháng 3 2023 lúc 18:31
Bài 1: Tính
a) \(\dfrac{2\times3\times6\times7}{12\times7\times9\times2}\)
b) \(\dfrac{3\times4\times30\times56}{9\times8\times7\times8\times20}\)
(Các bạn tách ra rồi tính)
tính :\(\frac{1}{1\times2\times3}+\frac{1}{2\times3\times4}+\frac{1}{3\times4\times5}+\frac{1}{4\times5\times6}+\frac{1}{5\times6\times7}+\frac{1}{6\times7\times8}+\frac{1}{7\times8\times9}+\frac{1}{8\times9\times10}\)
\(\frac{1}{1.2.3}+\frac{1}{2.3.4}+...+\frac{1}{8.9.10}=\frac{1}{2}.\left(\frac{1}{1.2}-\frac{1}{2.3}\right)+\frac{1}{2}.\left(\frac{1}{2.3}-\frac{1}{3.4}\right)+...+\frac{1}{2}.\left(\frac{1}{8.9}-\frac{1}{9.10}\right)\)
\(=\frac{1}{2}.\left(\frac{1}{1.2}-\frac{1}{2.3}+\frac{1}{2.3}-\frac{1}{3.4}+...+\frac{1}{8.9}-\frac{1}{9.10}\right)\)
\(\frac{1}{2}.\left(\frac{1}{1.2}-\frac{1}{9.10}\right)=\frac{1}{2}.\frac{22}{45}=\frac{11}{45}\)
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Tính nhanh:\(\frac{1\times2\times3+2\times4\times6+3\times6\times9+4\times8\times12+5\times10\times15}{1\times3\times5+2\times6\times10+3\times9\times15+4\times12\times20+5\times15\times25}-\frac{1+2+3+2+4+6+3+6+9+4+8+12+5+10+15}{1+3+5+2+6+10+3+9+15+4+12+20+5+15+25}\)
giúp với!
Tính: \(\dfrac{2\times3\times8}{4\times5\times6\times7}\)
\(=\dfrac{2^4\cdot3}{2^3\cdot5\cdot3\cdot7}=\dfrac{2}{5\cdot7}=\dfrac{2}{35}\)
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CHO A = \(\frac{2\times9\times8+3\times12\times10+4\times15\times12+...+98\times297\times200}{2\times3\times4+3\times4\times5+4\times5\times6+...+98\times99\times100}\)
TÍNH A\(^2\)
\(A=\frac{2\cdot9\cdot8+3\cdot12\cdot10+4\cdot15\cdot12+...+98\cdot297\cdot200}{2\cdot3\cdot4+3\cdot4\cdot5+4\cdot5\cdot6+...+98\cdot99\cdot100}\)
\(=\frac{2\cdot1\cdot3\cdot3\cdot4\cdot2+3\cdot1\cdot4\cdot3\cdot5\cdot2+...+98\cdot1+99\cdot3+100\cdot2}{2\cdot3\cdot4+3\cdot4\cdot5+...+98\cdot99\cdot100}\)
\(=\frac{1\cdot3\cdot2\cdot\left(2\cdot3\cdot4+3\cdot4\cdot5+...+98\cdot99\cdot100\right)}{2\cdot3\cdot4+3\cdot4\cdot5+...+98\cdot99\cdot100}\)
\(=1\cdot3\cdot2\)
\(=6\)
\(A^2=6^2=36\)
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C=\(\frac{1\times5\times6+2\times10\times12+24\times8\times10}{1\times3\times5+2\times6\times10+8\times6\times20}\)
\(C=\frac{1.5.6+2.10.12+24.8.10}{1.3.5+2.6.10+8.6.20}\)
\(C=\frac{1.5.6.\left(1^3+2^3+8^2\right)}{1.3.5.\left(1^3+2^3+8^2\right)}=\frac{6}{3}=2\)
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Bạn nên tách tử số và mẫu số ra thì sẽ tính được .
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toán lop may the
\(y=\frac{1\times2\times3+2\times4\times6+4\times8\times12+8\times16\times24}{2\times3\times4+4\times6\times8+8\times12\times16+16\times24\times32}\frac{ }{ }\)
\(y=\frac{1x2x3+2x4x6+4x8x12+8x16x24}{2x3x4+4x6x8+8x12x16+16x24x32}\)
\(y=\frac{1}{4}\)
tích nha . Đúng 100% luôn.
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Rút gọn các phân số sau:
a,\(\frac{3\times4\times7}{12\times8\times9}\)
b,\(\frac{4\times5\times6}{12\times10\times8}\)
c,\(\frac{5\times6\times7\times9}{12\times7\times27}\)
d,\(\frac{5\times6\times7}{12\times14\times15}\)
\(a,\frac{3\times4\times7}{12\times8\times9}\)
\(=\frac{3\times4\times7}{3\times4\times8\times9}\)
\(=\frac{7}{72}\)
\(b,\frac{4\times5\times6}{12\times10\times8}\)
\(=\frac{4\times5\times3\times2}{4\times3\times5\times2\times8}\)
\(=\frac{1}{8}\)
\(c,\frac{5\times6\times7\times9}{12\times7\times27}\)
\(=\frac{5\times6\times7\times9}{6\times2\times7\times9\times3}\)
\(=\frac{5}{6}\)
\(d,\frac{5\times6\times7}{12\times14\times15}\)
\(=\frac{5\times6\times7}{6\times2\times7\times2\times5\times3}\)
\(=\frac{1}{12}\)
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a) \(\frac{3\times4\times7}{12\times8\times9}=\frac{3\times4\times7}{3\times4\times8\times9}=\frac{7}{8\times9}=\frac{7}{72}\)
b) \(\frac{4\times5\times6}{12\times10\times8}=\frac{4\times5\times6}{6\times2\times2\times5\times4\times2}=\frac{1}{2\times2\times2}=\frac{1}{8}\)
c) \(\frac{5\times6\times7\times9}{12\times7\times27}=\frac{5\times6\times9}{12\times27}=\frac{5\times6\times9}{2\times6\times3\times9}=\frac{5}{2\times3}=\frac{5}{6}\)
d) \(\frac{5\times6\times7}{12\times14\times15}=\frac{5\times6\times7}{2\times6\times2\times7\times3\times5}=\frac{1}{2\times2\times3}=\frac{1}{12}\)
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a) \(\frac{3\times4\times7}{12\times8\times9}=\frac{3\times4\times7}{3\times4\times8\times9}=\frac{7}{8\times9}=\frac{7}{72}\)
b) \(\frac{4\times5\times6}{12\times10\times8}=\frac{4\times5\times6}{6\times2\times2\times5\times4\times2}=\frac{1}{2\times2\times2}=\frac{1}{8}\)
c) \(\frac{5\times6\times7\times9}{12\times7\times27}=\frac{5\times6\times9}{12\times27}=\frac{5\times6\times9}{2\times6\times3\times9}=\frac{5}{2\times3}=\frac{5}{6}\)
d) \(\frac{5\times6\times7}{12\times14\times15}=\frac{5\times6\times7}{2\times6\times2\times7\times3\times5}=\frac{1}{2\times2\times3}=\frac{1}{12}\)
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\(\frac{1}{2\times3}+\frac{1}{3\times4}+\frac{1}{4\times5}+\frac{1}{5\times6}+\frac{1}{6\times7}+\frac{1}{7\times8}+\frac{1}{8\times9}+\frac{1}{9\times10}\)
1/2.3+1/3.4+1/4.5+1/5.6+1/6.7+1/7.8+1/8.9+1/9.10
=1/2-1/3+1/3-1/4+1/4-1/5+1/5-1/6+1/6+1/7-1/7+1/8-1/8+1/9+1/9-1/10
=1/2-1/10
=5/10-1/10
=4/10=2/5
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\(\frac{1}{2x3}+\frac{1}{3x4}+\frac{1}{4x5}+\frac{1}{5x6}+\frac{1}{6x7}+\frac{1}{8x9}+\frac{1}{9x10}\)
\(\frac{1}{2}-\frac{1}{3}+\frac{1}{3}-\frac{1}{4}+\frac{1}{4}-\frac{1}{5}+\frac{1}{5}-\frac{1}{6}+\frac{1}{6}-\frac{1}{7}+\frac{1}{7}-\frac{1}{8}+\frac{1}{8}-\frac{1}{9}+\frac{1}{9}-\frac{1}{10}\)
\(\frac{1}{2}-\frac{1}{10}\)
\(\frac{2}{5}\)
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= 1/2-1/3+1/3-1/4+1/4-1/5+1/5-1/6+1/6-1/7+1/7-1/8+1/8-1/9+1/9-1/10
= 1/2-0-0-0-0-0-0-0-0-1/10
=1/2 - 1/10
=2/5
tớ trước nhé
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