Thực hiện phép tính sau:
\(\frac{21^4}{27.\left(-343\right)}+7\)
Help Me
thực hiện phép tính :
b, \(\left(\frac{-2}{9}\right)-\left(\frac{-1}{21}\right)+\left(\frac{-3}{5}\right)-\left(\frac{-1}{2}\right)-\left(-1\frac{13}{8}\right)-\frac{1}{7}-\frac{9}{35}\)
làm ơn help me với
bấm máy tính ra kết quả là 983/504
Baif 1: thực hiện phép tính( hợp lý nếu có thể )
\(\frac{21^4}{27.\left(-343\right)}\)\(\)
Bài 2: tìm các số a, b, c biết:
\(\frac{a}{4}=\frac{b}{5}=\frac{c}{2}\)và a+b-c=21
1/ Bg
\(\frac{21^4}{27.\left(-343\right)}\)= \(\frac{\left(3.7\right)^4}{3^3.\left(-7\right)^3}\)
= \(\frac{3^4.7^4}{3^3.\left(-7\right)^3}\)
= \(\frac{3.\left(-7\right)}{1.1}\)
= 3.(-7)
= -21
2/ Bg
Ta có: \(\frac{a}{4}=\frac{b}{5}=\frac{c}{2}\)và a + b - c = 21 (a, b, c thuộc Z)
Áp dụng tính chất dãy tỉ số bằng nhau, ta có:
\(\frac{a}{4}=\frac{b}{5}=\frac{c}{2}=\frac{a+b-c}{4+5-2}=\frac{21}{7}\)= 3
=> a = 3.4 = 12
=> b = 3.5 = 15
=> c = 3.2 = 6
Vậy a = 12, b = 15 và c = 6
\(\frac{21^4}{27.\left(-343\right)}+7\)
\(=\frac{\left(3.7\right)^4}{3^3.\left(-7\right)^3}+7\)
\(=\frac{3^4.7^4}{3^3.\left(-7\right)^3}+7\)
=\(\) 3.(-7)+7
= -14
\(\frac{21^4}{27.\left(-343\right)}+7\)
=> \(\frac{\left(3.7\right)^4}{3^3.\left(-7\right)^3}+7=>\frac{3^3.3.7^3.7}{3^3.\left(-7\right)^3}+7\)
=> 3 . (-7) + 7
= -21 + 7 = -14
\(\frac{21^4}{27.\left(-343\right)}+7\)
= \(\frac{\left(3.7\right)^4}{3^3.\left(-7\right)^3}+7\)
= \(\frac{3^4.7^4}{3^3.\left(-7\right)^3}+7\)
= 3.(-7) + 7
= (-21) + 7
= -14.
Chúc bạn học tốt!
- Thực hiện phép tính ( hợp lí nếu có thể )
\(\left(5-\frac{2}{3}+\frac{3}{7}\right):\left(24\frac{4}{21}-25\frac{8}{21}\right)\)
- Trả lời đúng mik tick cho nhá
\(\left(5-\frac{2}{3}+\frac{3}{7}\right):\left(24-25+\frac{4}{21}-\frac{8}{21}\right)\)
\(\left(\frac{5.21-14+9}{21}\right):\left(\frac{-21-4}{21}\right)\)=\(\left(\frac{5.21-5}{21}\right).\left(\frac{21}{-25}\right)\)=\(\frac{5\left(21-1\right)}{\left(-5\right).5}=\frac{20}{-5}\)
=-4
thực hiện phép tính sau một cách nhanh nhất:
\(1\frac{5}{7}\cdot0.75-\frac{6}{7}\cdot1\frac{1}{3}+\frac{6}{7}\)
\(2017\cdot2018\left(\frac{2016}{2017}-\frac{2016}{2018}\right)\)
\(\left(\frac{1}{2}-1\right)\left(\frac{1}{3}-1\right)\left(\frac{1}{4}-1\right)....\left(\frac{1}{100}-1\right)\)
\(\frac{1023}{2+2^2+2^3+....+2^{10}}\)GIÚP MÌNH VỚI!HELP ME!
\(=\frac{12}{7}\cdot\frac{3}{4}-\frac{6}{7}\cdot\frac{4}{3}+\frac{6}{7}\)
\(=\frac{6}{7}\left(\frac{3}{2}-\frac{4}{3}+1\right)\)
\(=\frac{6}{7}\left(\frac{1}{6}+1\right)=\frac{6}{7}\cdot\frac{7}{6}=1\)
2.
\(=2017\cdot2018\cdot\left[\left(2016\cdot2018\right)-\left(2016\cdot2017\right)\right]\)
\(=2017\cdot2018\cdot2016\left(2018-2017\right)=2016\cdot2017\cdot2018\)
3.
\(\left(\frac{1}{2}-1\right)\left(\frac{1}{3}-1\right)\left(\frac{1}{4}-1\right)....\left(\frac{1}{100}-1\right)=\frac{1}{2}\cdot\frac{2}{3}\cdot\frac{3}{4}\cdot....\cdot\frac{99}{100}\)
\(=\frac{1}{100}\)
4.
\(=\frac{1+2+2^2+2^4+...+2^9}{2\left(1+2+2^2+2^3+2^4+...+2^9\right)}\)
\(=\frac{1}{2}\)
mình chỉ làm được câu 3 thôi
có \(\left(\frac{1}{2}-1\right)\left(\frac{1}{3}-1\right)....\left(\frac{1}{100}-1\right)\)
\(=\frac{-1}{2}\times\frac{-2}{3}\times....\times\frac{-99}{100}\)
\(=\frac{\left(-1\right)\left(-2\right)....\left(-99\right)}{2\times3\times....\times100}\)
\(=\frac{-\left(1\times2\times....\times99\right)}{2\times3\times....\times100}\)
\(=\frac{-1}{100}\)
Thực hiện các phép tính sau:
\(\frac{\sqrt{7}-5}{2}-\frac{6-2\sqrt{7}}{4}+\frac{6}{\sqrt{7}-2}-\frac{5}{4+\sqrt{7}}\)
help me!!! PLSSSSS!!!!!
thực hiện phép tính (tính nhanh nếu có thể) :
a)\(1\frac{3}{19}+\frac{8}{21}-\frac{3}{19}+0.5+\frac{13}{21}\)
b)\(\left(-\frac{3}{4}+\frac{2}{7}\right):\frac{3}{7}+\left(\frac{5}{7}+\frac{-1}{4}\right):\frac{3}{7}\)
c)\(\left(\frac{1}{6}\right)^7\times6\)
d)\(\left(\frac{-1}{2}\right)^3+\frac{1}{2}:3\)
a) \(1\frac{3}{19}+\frac{8}{21}-\frac{3}{19}+0.5+\frac{13}{21}\)
\(=\left(1\frac{3}{19}-\frac{3}{19}\right)+\left(\frac{8}{21}+\frac{13}{21}\right)+0.5\)
\(=1+1+0.5=2.5\)
b) \(\left(-\frac{3}{4}+\frac{2}{7}\right):\frac{3}{7}+\left(\frac{5}{7}+\frac{-1}{4}\right):\frac{3}{7}\)
\(=\left(\frac{-3}{4}+\frac{2}{7}+\frac{5}{7}+\frac{-1}{4}\right):\frac{3}{7}\)
\(=0:\frac{3}{7}=0\)
Thực hiện phép tính
a, \(9^8:\left(27^3.81^2\right)\)
b,\(\left(125^4.7^{10}\right):\left(5^{12}.343^3\right)\)
a) \(9^8=\left(3^2\right)^8=3^{16}\)
\(27^3=\left(3^3\right)^3=3^9\)
\(81^2=\left(3^4\right)^2=3^8\)
\(\Leftrightarrow3^{16}:\left(3^9.3^8\right)\)
\(\Leftrightarrow3^{16}:3^{17}\)
\(\Leftrightarrow3^{-1}=\frac{1}{3}\)
a) 9́́́8 : ̣(273 . 812)= 316 : 39 . 38 = 315
b) \(125^4=\left(5^3\right)^4=5^{12}\)
\(343^3=\left(7^3\right)^3=7^9\)
\(=\frac{5^{12}.7^{10}}{5^{12}.7^9}\)
\(=\frac{7^{10}}{7^9}\)
\(=7\)
bài 3 thực hiện phép tính
a\(\dfrac{5}{8}+\dfrac{3}{17}+\dfrac{4}{18}+\dfrac{20}{-17}+\dfrac{-2}{9}+\dfrac{21}{56}\)
b\(\left(\dfrac{9}{16}+\dfrac{8}{-27}\right)+\left(1+\dfrac{7}{16}+\dfrac{-19}{27}\right)\)
c\(\left(\dfrac{13}{5}+\dfrac{7}{16}\right)+\left(\dfrac{-15}{16}+\dfrac{6}{15}\right)\) d \(\left(6-2\dfrac{4}{5}\right).3\dfrac{1}{8}-1\dfrac{3}{5}:\dfrac{1}{4}\)
a) Ta có: \(\dfrac{5}{8}+\dfrac{3}{17}+\dfrac{4}{18}+\dfrac{20}{-17}+\dfrac{-2}{9}+\dfrac{21}{56}\)
\(=\left(\dfrac{3}{17}-\dfrac{20}{17}\right)+\left(\dfrac{2}{9}-\dfrac{2}{9}\right)+\left(\dfrac{5}{8}+\dfrac{3}{8}\right)\)
\(=-1+1=0\)
b) Ta có: \(\left(\dfrac{9}{16}+\dfrac{8}{-27}\right)+\left(1+\dfrac{7}{16}+\dfrac{-19}{27}\right)\)
\(=\left(\dfrac{9}{16}+\dfrac{7}{16}\right)+\left(\dfrac{-8}{27}-\dfrac{19}{27}\right)+1\)
=1-1+1=1