Hãy nhập câu hỏi của bạn vào đây, nếu là tài khoản VIP, bạn sẽ được ưu tiên trả lời.
a) \(A=\dfrac{-45.58-45.42}{2+4+6+...+16+18}\)
\(A=-\dfrac{45\left(58+42\right)}{\dfrac{\left(18-2\right):2+1}{2}.\left(2+18\right)}\)
\(A=\dfrac{-45.100}{\dfrac{5}{2}.20}\)
\(A=-\dfrac{45.100}{50}\)
\(A=-90\)
b) \(1-\left[\left(5\dfrac{3}{8}+x-7\dfrac{5}{24}\right):\left(-16\dfrac{2}{3}\right)\right]=0\)
\(\Rightarrow\left(5\dfrac{3}{8}+x-7\dfrac{5}{24}\right):\left(-16\dfrac{2}{3}\right)=1\)
\(\Rightarrow\left(\dfrac{43}{8}+x-\dfrac{173}{24}\right):\left(-\dfrac{46}{3}\right)=1\)
\(\Rightarrow\left(\dfrac{129}{24}-\dfrac{173}{24}+x\right).\left(-\dfrac{3}{46}\right)=1\)
\(\Rightarrow\left(-\dfrac{44}{24}+x\right).\left(-\dfrac{3}{46}\right)=1\)
\(\Rightarrow\left(-\dfrac{11}{6}+x\right).\left(-\dfrac{3}{46}\right)=1\)
\(\Rightarrow-\dfrac{11}{6}+x=1.\left(-\dfrac{46}{3}\right)\)
\(\Rightarrow-\dfrac{11}{6}+x=-\dfrac{46}{3}\)
\(\Rightarrow x=-\dfrac{46}{3}+\dfrac{11}{6}\)
\(\Rightarrow x=-\dfrac{92}{6}+\dfrac{11}{6}\)
\(\Rightarrow x=-\dfrac{81}{6}\)
\(\Rightarrow x=-\dfrac{27}{2}\)
\(\frac{-45.58-45.42}{2+4+6+...+16+18}=\frac{-45.\left(42+58\right)}{2+4+6+...+16+18}=\frac{-45.100}{2+4+6+...+16+18}=\frac{-4500}{2+4+6+...+16+18}\)
Ta có:2+4+6+...+18
Dãy số trên có:(18-2):2+1=9(số)
Tổng dãy trên là:(18+2).9:2=90
=>\(\frac{-4500}{2+4+6+...+16+18}=-\frac{4500}{90}=-50\)
a) \(\frac{6}{7}+\frac{5}{8}:5-\frac{3}{16}.\left(-2\right)^2\)
\(=\frac{6}{7}+\frac{1}{8}-\frac{3}{16}.4\)
\(=\frac{55}{56}-\frac{3}{4}\)
\(=\frac{13}{56}\)
Câu b) tạm thời ko bít làm =.=
Bài 1 :
\(d)\) \(\frac{4^5+4^5+4^5+4^5}{3^5+3^5+3^5}.\frac{6^5+6^5+6^5+6^5+6^5+6^5}{2^5+2^5}=2x\)
\(\Leftrightarrow\)\(\frac{4^5.4}{3^5.3}.\frac{6^5.6}{2^5.2}=2x\)
\(\Leftrightarrow\)\(\frac{4^6}{3^6}.\frac{6^6}{2^6}=2x\)
\(\Leftrightarrow\)\(\frac{2^{12}}{3^6}.\frac{2^6.3^6}{2^6}=2x\)
\(\Leftrightarrow\)\(\frac{2^{12}}{3^6}.\frac{3^6}{1}=2x\)
\(\Leftrightarrow\)\(2^{12}=2x\)
\(\Leftrightarrow\)\(x=\frac{2^{12}}{2}\)
\(\Leftrightarrow\)\(x=2^{11}\)
\(\Leftrightarrow\)\(x=2048\)
Vậy \(x=2048\)
Chúc bạn học tốt ~
Bài 1 :
\(a)\) Ta có :
\(4+\frac{x}{7+y}=\frac{4}{7}\)
\(\Leftrightarrow\)\(\frac{x}{7+y}=\frac{4}{7}-4\)
\(\Leftrightarrow\)\(\frac{x}{7+y}=\frac{-24}{7}\)
\(\Leftrightarrow\)\(\frac{x}{-24}=\frac{7+y}{7}\)
Áp dụng tính chất dãy tỉ số bằng nhau ta có :
\(\frac{x}{-24}=\frac{7+y}{7}=\frac{x+7+y}{-24+7}=\frac{22+7}{-17}=\frac{29}{-17}=\frac{-29}{17}\)
Do đó :
\(\frac{x}{-24}=\frac{-29}{17}\)\(\Rightarrow\)\(x=\frac{-29}{17}.\left(-24\right)=\frac{696}{17}\)
\(\frac{7+y}{7}=\frac{-29}{17}\)\(\Rightarrow\)\(y=\frac{-29}{17}.7-7=\frac{-322}{17}\)
Vậy \(x=\frac{696}{17}\) và \(y=\frac{-322}{17}\)
Chúc bạn học tốt ~
