\(\frac{5}{6}+\frac{2}{6}=?\)
ai tick mk mk tick cho 3 cái
\(\frac{5}{6}\)+\(\frac{7}{6}\)=?
ai tick mk mk tick cho 3 cái
\(\frac{5}{6}\)+\(\frac{7}{6}\)=\(\frac{12}{6}\)=2
ai k mk k cho 3 k
\(\frac{5}{6}\)+\(\frac{7}{6}\)=\(\frac{12}{6}\)=2
ai k mk k cho 3 k
\(\frac{5}{6}\)+\(\frac{7}{6}\)=\(\frac{12}{6}\)=2
ai k mk k cho 3 k
\(\frac{5}{7}\)+\(\frac{9}{7}\)= ?
ai tick mk mk tick cho 3 cái
a, tìm x
\(\frac{1}{2}.x+\frac{3}{5}.\left(x-2\right)=3\)
b, chứng tỏ rằng:\(\frac{1}{2^2}+\frac{1}{4^2}+\frac{1}{6^2}+...+\frac{1}{100^2}< \frac{1}{2}\)
giải thưởng:
- ai giải được câu a; mk và 3 ngừ bạn của m sẽ tick cho ( có lời giải đàng hoàng)
- ai giải được câu b , mk và 5 ngừ bạn của mk sẽ tick cho (có lời giải đàng hoàng)
- ai giải được cả hai câu , mk và 7 ngừ bạn của mk sẽ tick cho ( có lời giải đàng hoàng)
A = 1/2^2 + 1/3^2 + 1/4^2 + ... + 1/100^2
1/2^2 < 1/1*2
1/3^2 < 1/2*3
1/4^2 < 1/3*4
...
1/100^2 < 1/99*100
=> A < 1/1*2 + 1/2*3 + 1/3*4 + ... + 1/99*100
=> A < 1 - 1/2 + 1/2 - 1/3 + 1/3 - 1/4 + ... + 1/99 - 1/100
=> A < 1 - 1/100
=> A < 1
minh deo can ban k dau :((
\(a,\frac{1}{2}x+\frac{3}{5}(x-2)=3\)
\(\Rightarrow\frac{1}{2}x+\frac{3}{5}x-\frac{6}{5}=3\)
\(\Rightarrow\left[\frac{1}{2}+\frac{3}{5}\right]x=3+\frac{6}{5}\)
\(\Rightarrow\left[\frac{5}{10}+\frac{6}{10}\right]x=\frac{21}{5}\)
\(\Rightarrow\frac{11}{10}x=\frac{21}{5}\)
\(\Rightarrow x=\frac{21}{5}:\frac{11}{10}=\frac{21}{5}\cdot\frac{10}{11}=\frac{21}{1}\cdot\frac{2}{11}=\frac{42}{11}\)
Vậy x = 42/11
1. \(\frac{3}{1X4}+\frac{3}{4X7}+\frac{3}{7X10}+.........+\frac{3}{40X43}\)
2. \(\frac{2}{2}+\frac{2}{6}+\frac{2}{12}+........+\frac{2}{90}\)
Giúp mk nha ai lm nhanh mk tick cho
Cái dâu X là dấu nhân nha
1. \(\frac{3}{1.4}+\frac{3}{4.7}+\frac{3}{7.10}+...+\frac{3}{40.43}\)
\(=1-\frac{1}{4}+\frac{1}{4}-\frac{1}{7}+\frac{1}{7}-\frac{1}{10}+...+\frac{1}{40}-\frac{1}{43}\)
\(=1-\frac{1}{43}\)
\(=\frac{42}{43}\)
2. Đặt \(A=\frac{2}{2}+\frac{2}{6}+\frac{2}{12}+...+\frac{2}{90}\)
\(=2.\left(\frac{1}{1.2}+\frac{1}{2.3}+\frac{1}{3.4}+...+\frac{1}{9.10}\right)\)
\(=2.\left(1-\frac{1}{2}+\frac{1}{2}-\frac{1}{3}+\frac{1}{3}-\frac{1}{4}+...+\frac{1}{9}-\frac{1}{10}\right)\)
\(=2.\left(1-\frac{1}{10}\right)\)
\(=2.\frac{9}{10}\)
\(=\frac{9}{5}\)
Ủng hộ mk nha !!! ^_^
1) 3/1×4 + 3/4×7 + 3/7×10 + ... + 3/40×43
= 1 - 1/4 + 1/4 - 1/7 + 1/7 - 1/10 + ... + 1/40 - 1/43
= 1 - 1/43
= 42/43
2) 2/2 + 2/6 + 2/12 + ... + 2/90
= 2 × (1/2 + 1/6 + 1/12 + ... + 1/90)
= 2 × (1/1×2 + 1/2×3 + 1/3×4 + ... + 1/9×10)
= 2 × (1 - 1/2 + 1/2 - 1/3 + 1/3 - 1/4 + ... + 1/9 - 1/10)
= 2 × (1 - 1/10)
= 2 × 9/10
= 9/5
1) 3/1×4 + 3/4×7 + 3/7×10 + ... + 3/40×43
= 1 - 1/4 + 1/4 - 1/7 + 1/7 - 1/10 + ... + 1/40 - 1/43
= 1 - 1/43
= 42/43
2) 2/2 + 2/6 + 2/12 + ... + 2/90
= 2 × (1/2 + 1/6 + 1/12 + ... + 1/90)
= 2 × (1/1×2 + 1/2×3 + 1/3×4 + ... + 1/9×10)
= 2 × (1 - 1/2 + 1/2 - 1/3 + 1/3 - 1/4 + ... + 1/9 - 1/10)
= 2 × (1 - 1/10)
= 2 × 9/10
= 9/5
\(\frac{x+6}{15}=\frac{5-x}{7}\)
GIÚP MK ĐI, MK CẦN GẤP LẮM, AI LÀM ĐC MK TICK CHO, NHA ^^
\(\frac{x+6}{15}=\frac{5-x}{7}\)
\(\Leftrightarrow\left(x+6\right).7=\left(5-x\right).15\)
\(\Leftrightarrow7x+42=75-15x\)
\(\Leftrightarrow7x+15x=75-42\)
\(\Leftrightarrow22x=33\)
\(\Leftrightarrow x=\frac{3}{2}\)
=> 7.(x+6)= 15.(5-x)
=> 7x +7.6=15.5-15x
=> 7x + 42= 75 -15x
=> 7x+15x=75-42
=> 22x=33
=>x= 1,5
\(\frac{x+6}{15}=\frac{5-x}{7}\)
\(\Rightarrow\frac{x+6}{15}-\frac{5-x}{7}=0\)
\(\Rightarrow\frac{7.\left(x+6\right)}{7.15}+\frac{15.\left(x-5\right)}{7.15}=0\)
\(\Rightarrow\frac{7x+42}{105}+\frac{15x-75}{105}=0\)
\(\Rightarrow\frac{7x+42+15x-75}{105}=0\)
\(\Rightarrow\frac{22x-33}{105}=0\)
\(\Rightarrow22x+33=0\Rightarrow22x=33\)
\(\Rightarrow x=\frac{33}{22}=\frac{3}{2}\)
\(\frac{5\sqrt{6-1}}{\sqrt{6}+1}\) + \(\frac{\sqrt{2}-\sqrt{3}}{\sqrt{2}+\sqrt{3}}\)+ \(\sqrt{3-2\sqrt{2}}\)
Giúp mk vs mk cần gấp :) Ai nhanh mk tick :)
\(\frac{5\left(\sqrt{6}-1\right)\left(\sqrt{6}-1\right)}{\left(\sqrt{6}+1\right)\left(\sqrt{6}-1\right)}+\frac{\left(\sqrt{2}-\sqrt{3}\right)\left(\sqrt{2}-\sqrt{3}\right)}{\left(\sqrt{2}+\sqrt{3}\right)\left(\sqrt{2}-\sqrt{3}\right)}+\sqrt{\left(\sqrt{2}\right)^2-2\sqrt{2}+1}\)
\(=\frac{5\left(\sqrt{6}-1\right)^2}{5}-\frac{\left(\sqrt{2}-\sqrt{3}\right)^2}{1}+\sqrt{\left(\sqrt{2}-1\right)^2}\)
\(=\left(\sqrt{6}-1\right)^2-\left(\sqrt{2}-\sqrt{3}\right)^2+\left(\sqrt{2}-1\right)\)
\(=6-2\sqrt{6}+1-2+2\sqrt{6}-3+\sqrt{2}-1=\sqrt{2}\)
Tìm x:\(\left(\frac{1+2x}{4+2x}-\frac{x}{3x-6}-\frac{2x^2}{3x^2-12}\right):\frac{6+13x}{24-12}\)
Ai nhanh mk tick cho , mk cam on
Tìm x :
\(\frac{2\left(1+x\right)}{3}-\frac{5\left(2-x\right)}{6}=1\frac{1}{3}-\frac{3\left(2x+3\right)}{4}-1\frac{1}{2}\left(x+1\right)\)
Ai nhanh mk tick cho . mk cảm ơn nhiều
tim da thuc B biet:
\(B-\left(3x^6-4xy^5+\frac{1}{3}xy^2-\frac{3}{2}\right)=\left(7x^6-\frac{1}{2}xy^5-xy^2-\frac{1}{3}\right)\)
giup mk nha cac bn , ai co cach giai ro rang mk se tick 3 cai