a. 1/3+3/4+1/2=
b. 6/8+2/4+6/24=
c. 21/12-3/4=
d. 1/2+1/3+5/6=
e. 3/5+3/2+2=
Hãy nhập câu hỏi của bạn vào đây, nếu là tài khoản VIP, bạn sẽ được ưu tiên trả lời.
\(\left(2^2\div4\right).2^n=4\)
\(\Leftrightarrow\left(4\div4\right).2^n=4\)
\(\Leftrightarrow1.2^n=4\)
\(\Leftrightarrow2^n=4\)
\(\Leftrightarrow2^n=2^2\)
\(\Rightarrow n=2\)
Vậy \(n=2\)
\(1+2+3+4+...+n=190\)
Ta có:
\(\Leftrightarrow\left(n+1\right)n\div2=190\)
\(\Leftrightarrow\left(n+1\right)n=190.2\)
\(\Leftrightarrow\left(n+1\right)n=380\)
\(\Leftrightarrow\left(n+1\right)n=19.20\)
\(\Rightarrow n=19\)
Vậy \(n=19\)
\(X\div\frac{1}{4}=8\)
\(X=8\times\frac{1}{4}\)
\(X=\frac{8}{4}\Leftrightarrow X=2\)
Thay \(x=\frac{1}{2}\)và \(y=-\frac{1}{3}\)vào biểu thức :
\(3x^3y+6x^2y^2+3xy^3\)
\(=3.\left(\frac{1}{2}\right)^3.\left(-\frac{1}{3}\right)+6.\left(\frac{1}{2}\right)^2.\left(-\frac{1}{3}\right)^2+3.\frac{1}{2}.\left(-\frac{1}{3}\right)^3\)
\(=3.\frac{1}{8}.\left(-\frac{1}{3}\right)+6.\frac{1}{4}.\frac{1}{9}+3.\frac{1}{2}.\left(-\frac{1}{27}\right)\)
\(=\frac{3}{8}.\left(-\frac{1}{3}\right)+\frac{3}{2}.\frac{1}{9}+\frac{3}{2}.\left(-\frac{1}{27}\right)\)
\(=-\frac{1}{8}+\frac{1}{6}+-\frac{1}{18}\)
\(=\frac{1}{24}+-\frac{1}{18}=-\frac{1}{72}\)
\(\frac{5}{12}+\frac{1}{6}=\frac{5}{12}+\frac{2}{12}=\frac{7}{12}.\)