Tính nhanh
\(\frac{7}{5.9}+\frac{7}{9.11}+\frac{7}{11.13}+\frac{7}{13.15}+..+\frac{7}{2015.2017}\)
giup mk vs nha mk can gap lam
mk se tick cho ai lm dung
thank you, thank you.
tính
1/\(\frac{\left(\frac{3}{10}-\frac{4}{15}-\frac{7}{20}\right).\frac{5}{9}}{\left(\frac{1}{4}+\frac{1}{7}-\frac{-3}{35}\right).\left(-1\frac{1}{3}\right)}\)
2/\(\frac{0,6-\frac{1}{3}+\frac{3}{11}}{1,4-\frac{7}{9}+\frac{7}{11}}-\frac{\frac{1}{3}-0,25+\frac{1}{5}}{1\frac{1}{6}-0,875+0,7}\)
các bn lm giúp mk vs!!!!
mk đang cần gấp lắm nha!!!!!!!!!
ai lm nhanh nhất đúng đủ trình bày khoa học mk tick cho !!!!!!!1
bai 1 :thuc hien phep tinh
a)\(\frac{-5}{2}:\left(\frac{3}{4}-\frac{1}{2}\right)\) b) \(11\frac{3}{13}-\left(2\frac{4}{7}+5\frac{3}{13}\right)\) c)\(\left(\frac{-5}{24}+0,75+\frac{7}{12}\right):\left(-2\frac{1}{4}\right)^2\)
AI LAM NHANH VA DUNG THI MK SE TICK CHO NHA
MK DAG CAN GAP !!!!!!! CAC BAN LAM NHANH LEN NHA
a) \(\frac{\left(x+\frac{3}{4}\right)\cdot\frac{7}{2}-\frac{1}{6}}{-\left(\frac{4}{5}+\frac{1}{3}\right)\cdot\frac{1}{2}+1}=2\frac{33}{52}\)
b) \(\frac{\left(5-\frac{2}{7}\right)\cdot\frac{7}{9}:\frac{3}{5}}{\left(3x-\frac{5}{6}\right):\frac{1}{7}}=5\frac{5}{21}\)
Bài 7: Tìm x biết
CAC BAN GIUP MK NHA
AI CO CAU TRA LOI NHANH NHAT VA CHINH XAC NHAT THI MK TICK CHO
o0oNguyễno0o bn giúp mk nha bài này khó wa
Tính nhanh:
\(\frac{1}{5\text{ x }6}+\frac{1}{6\text{ x }7}+\frac{1}{7\text{ x }8}+\frac{1}{8\text{ x }9}\)\(+\frac{1}{9\text{ x }10}\)
Giúp mk nhanh nha, chiều này nộp bài rồi, mk sẽ tick cho những bn lm bài đầy đủ ( ghi đáp số k thì mk sẽ k tick)
#)Giải :
Đặt \(A=\frac{1}{5.6}+\frac{1}{6.7}+\frac{1}{7.8}+\frac{1}{8.9}+\frac{1}{9.10}\)
\(A=\frac{1}{5}-\frac{1}{6}+\frac{1}{6}-\frac{1}{7}+\frac{1}{7}-\frac{1}{8}+\frac{1}{8}-\frac{1}{9}+\frac{1}{9}-\frac{1}{10}\)
\(A=\frac{1}{5}-\frac{1}{10}\)
\(A=\frac{1}{10}\)
cho mk hỏi chút là tại sao ta lấy 1/5 - 1/6 r + 1/6....
\(A=\frac{1}{5\cdot6}+\frac{1}{6\cdot7}+\frac{1}{7\cdot8}+\frac{1}{8\cdot9}+\frac{1}{9\cdot10}\)
\(A=\frac{1}{5}-\frac{1}{6}+\frac{1}{6}-\frac{1}{7}+...+\frac{1}{9}-\frac{1}{10}\)
\(A=\frac{1}{5}-\frac{1}{10}\)
\(A=\frac{2}{10}-\frac{1}{10}=\frac{1}{10}\)
Cho biểu thức:
\(A=\frac{4}{7.31}+\frac{6}{7.41}+\frac{9}{10.41}+\frac{7}{10.57}\) \(B=\frac{7}{19.31}+\frac{5}{19.43}+\frac{3}{23.43}+\frac{11}{23.57}\)
Tính tỉ số \(\frac{A}{B}\)
Ai nhanh mik tick nha, mik can gap!!
Ta có:
\(\frac{A}{5}=\frac{4}{35\cdot31}+\frac{6}{35\cdot41}+\frac{9}{50\cdot41}+\frac{7}{50\cdot57}=\frac{35-31}{35\cdot31}+\frac{41-35}{35\cdot41}+\frac{50-41}{50\cdot41}+\frac{57-50}{50\cdot57}\) ( Ps cuối là\(\frac{57-50}{50.57}\) nha).
\(=\frac{1}{31}-\frac{1}{35}+\frac{1}{35}-\frac{1}{41}+\frac{1}{41}-\frac{1}{50}+\frac{1}{50}-\frac{1}{57}\)
\(\Rightarrow\frac{A}{5}=5\cdot\left(\frac{1}{31}-\frac{1}{57}\right)\)
Tương tự:
\(\frac{B}{2}=\frac{7}{38.31}+\frac{5}{38.43}+\frac{3}{43.46}+\frac{11}{46.57}=\frac{38-31}{38.31}+\frac{41-38}{38.41}+\frac{46-43}{43.46}+\frac{57-46}{46.57}\)
\(=\frac{1}{31}-\frac{1}{38}+\frac{1}{38}-\frac{1}{43}+\frac{1}{43}-\frac{1}{46}+\frac{1}{46}-\frac{1}{57}\)
\(\Rightarrow\frac{B}{2}=2\cdot\left(\frac{1}{31}-\frac{1}{57}\right)\)
Từ đó, suy ra:
\(\frac{A}{B}=\frac{5}{2}\)
Vậy \(\frac{A}{B}=\frac{5}{2}\)
P/s: Có gì thừa hay thiếu thì bạn thêm hoặc bớt đi nha.
~Hk tốt~
Tính giá tri biểu thức:\(A=81.\left[\frac{12-\frac{12}{7}-\frac{12}{289}-\frac{12}{85}}{4-\frac{4}{7}-\frac{4}{289}-\frac{4}{85}}:\frac{5+\frac{5}{13}+\frac{5}{169}+\frac{5}{91}}{6+\frac{6}{13}+\frac{6}{169}+\frac{6}{91}}\right].\frac{158158158}{711711711}\)
Giai nhanh zum nha ai giai nhanh nhat minh se tk cho. THANKS YOU VERY MATH.......!
\(A=81.\left[\frac{12-\frac{12}{7}-\frac{12}{289}-\frac{12}{85}}{4-\frac{4}{7}-\frac{4}{289}-\frac{4}{85}}:\frac{5+\frac{5}{13}+\frac{5}{169}+\frac{5}{91}}{6+\frac{6}{13}+\frac{6}{169}+\frac{6}{91}}\right].\frac{158158158}{711711711}\)
\(A=81.\left[\frac{12.\left(1-\frac{1}{7}-\frac{1}{289}-\frac{1}{85}\right)}{4.\left(1-\frac{1}{7}-\frac{1}{289}-\frac{1}{85}\right)}:\frac{5.\left(1+\frac{1}{13}+\frac{1}{169}+\frac{1}{91}\right)}{6.\left(1+\frac{1}{13}+\frac{1}{169}+\frac{1}{91}\right)}\right].\frac{158}{711}\)
\(A=81.\left(\frac{12}{4}:\frac{5}{6}\right).\frac{2}{9}\)
\(A=81.3.\frac{6}{5}.\frac{2}{9}\)
\(A=\frac{324}{5}\)
Nhớ là: THANKS YOU VERY "MUCH" chứ không phải là THANKS YOU VERY "MATH"!!!
\(A=81.\frac{158158158}{711711711}.\frac{12.\left(\frac{1}{7}-\frac{1}{289}-\frac{1}{85}\right)}{4.\left(\frac{1}{7}-\frac{1}{289}-\frac{1}{85}\right)}:\frac{5.\left(\frac{1}{13}+\frac{1}{169}+\frac{1}{91}\right)}{6.\left(\frac{1}{13}+\frac{1}{169}+\frac{1}{91}\right)}\)
\(=81.\frac{158}{711}.\frac{12}{4}:\frac{5}{6}=\frac{1422}{79}.3.\frac{6}{5}=\frac{1422.3.6}{79.5}=\frac{25596}{395}\)
tính
B=\(\frac{12-\frac{12}{7}-\frac{12}{289}-\frac{12}{85}}{4-\frac{4}{7}-\frac{4}{289}-\frac{4}{85}}:\frac{3+\frac{3}{13}+\frac{3}{169}+\frac{3}{91}}{7+\frac{7}{13}+\frac{7}{169}+\frac{7}{91}}\)
giải nhanh và rõ giùm mk nhé
mai mk phải nộp bài rùi
ai nhanh nhất mk sẽ k cho !!!
tính
a,\(\frac{-3}{26}+2\frac{4}{69}\)
b,\(-2.\frac{-38}{21}.\frac{-7}{4}.-\frac{3}{8}\)
nhanh nhanh dùm mk nha!ai nhanh và đúng mk tick cho
Tính:
b) \(-2.\frac{-38}{21}.\frac{-7}{4}.-\frac{3}{8}\)
= \(\frac{\left(-2\right).\left(-38\right).\left(-7\right).\left(-3\right)}{21.4.8}\)
= \(\frac{-1.-19.1}{1.2.4}=\frac{19}{8}\)
// Học tốt!
\(\frac{x-7}{3}\) \(=\frac{-27}{7-x}\)
Tìm x
ai lm nhanh va dung mk tick
\(\frac{x-7}{3}=\frac{-27}{7-x}\)
\(\Leftrightarrow\left(x-7\right)\left(7-x\right)=\left(-27\right).3\)
\(\Leftrightarrow7x-x^2-49+7x=-81\)
\(\Leftrightarrow-x^2+14x-49=-81\)
\(\Leftrightarrow-x^2+14x+32=0\)
\(\Leftrightarrow x^2-14x-32=0\)
\(\Leftrightarrow x^2+2x-16x-32=0\)
\(\Leftrightarrow x\left(x+2\right)-16\left(x+2\right)=0\)
\(\Leftrightarrow\left(x+2\right)\left(x-16\right)=0\)
\(\Leftrightarrow\orbr{\begin{cases}x+2=0\\x-16=0\end{cases}\Leftrightarrow\orbr{\begin{cases}x=-2\\x=16\end{cases}}}\)