Question

[Đặng Nguyễn Tùng Lâm]

Answer 1

[Đặng Nguyễn Tùng Lâm]

bài 6 làm như thế nào hả các bạn

Answer 2

[Nguyễn Lê Phước Thịnh]

Bài 1:

\(A=-\frac25+\frac34\cdot\frac29\)

\(=-\frac25+\frac{6}{36}\)

\(=-\frac25+\frac16=-\frac{12}{30}+\frac{5}{30}=-\frac{7}{30}\)

\(B=\frac38\cdot\frac{-13}{15}-\frac38\cdot\frac{2}{15}+1\frac12\)

\(=\frac38\left(-\frac{13}{15}-\frac{2}{15}\right)+\frac32\)

\(=-\frac38+\frac32=-\frac38+\frac{12}{8}=\frac98\)

\(C=-\frac78+\frac{9}{10}\cdot\frac23\)

\(=-\frac78+\frac93\cdot\frac{2}{10}\)

\(=-\frac78+\frac35=-\frac{35}{40}+\frac{24}{40}=-\frac{11}{40}\)

\(D=\frac{5}{11}\cdot\frac{-17}{31}-\frac{5}{11}\cdot\frac{14}{31}+1\frac12\)

\(=-\frac{5}{11}\left(\frac{17}{31}+\frac{14}{31}\right)+\frac32\)

\(=-\frac{5}{11}+\frac32=-\frac{10}{22}+\frac{33}{22}=\frac{23}{22}\)

Bài 2:

a: \(\frac65-\frac15\cdot\frac{10}{3}\)

\(=\frac65-\frac{10}{5}\cdot\frac13=\frac65-\frac23\)

\(=\frac{18}{15}-\frac{10}{15}=\frac{8}{15}\)

b: \(\frac{11}{24}-\frac{5}{41}+\frac{13}{24}+0,5-\frac{36}{41}\)

\(=\left(\frac{11}{24}+\frac{13}{24}\right)-\left(\frac{5}{41}+\frac{36}{41}\right)+0,5\)

\(=1-1+0,5=0,5\)

c: \(\frac12\cdot\frac{-3}{4}+\frac12\cdot\frac{-1}{4}+\frac23\)

\(=\frac12\left(-\frac34-\frac14\right)+\frac23\)

\(=-\frac12+\frac23=-\frac36+\frac46=\frac16\)

d: \(\frac13\cdot\frac{-5}{6}+\frac13\cdot\frac{-1}{6}+\frac12\)

\(=\frac13\left(-\frac56-\frac16\right)+\frac12\)

\(=-\frac13+\frac12=\frac16\)

Bài 3:

a: \(\frac{6}{x-7}=\frac{-3}{7}\)

=>\(\frac{6}{x-7}=\frac{-6}{14}\)

=>x-7=-14

=>x=-14+7=-7

b: \(-\frac35-x=\frac12\)

=>\(x=-\frac35-\frac12=-\frac{6}{10}-\frac{5}{10}=-\frac{11}{10}\)

c: \(x-\frac{3}{10}=\frac{7}{15}\cdot\frac{3}{14}\)

=>\(x-\frac{3}{10}=\frac{7}{14}\cdot\frac{3}{15}=\frac12\cdot\frac15=\frac{1}{10}\)

=>\(x=\frac{1}{10}+\frac{3}{10}=\frac{4}{10}=\frac25\)

d: \(\frac{5}{14}-x=-\frac{17}{36}:\frac{51}{18}\)

=>\(\frac{5}{14}-x=-\frac{17}{36}\cdot\frac{18}{51}=-\frac{17}{51}\cdot\frac{18}{36}\)

=>\(\frac{5}{14}-x=-\frac13\cdot\frac12=-\frac16\)

=>\(x=\frac{5}{14}+\frac16=\frac{15}{42}+\frac{7}{42}=\frac{22}{42}=\frac{11}{21}\)

e: \(-\frac34x+\frac14\left(x-1\right)=-\frac{12}{5}\)

=>\(-\frac34x+\frac14x-\frac14=-\frac{12}{5}\)

=>\(-\frac24x=-\frac{12}{5}+\frac14=-\frac{48}{20}+\frac{5}{20}=-\frac{43}{20}\)

=>\(\frac{x}{2}=\frac{43}{20}\)

=>\(x=\frac{43}{20}\cdot2=\frac{43}{10}\)

f: \(\left(2x-\frac49\right)\left(3-11x\right)=0\)

=>\(\left[\begin{array}{l}2x-\frac49=0\\ 3-11x=0\end{array}\right.\Rightarrow\left[\begin{array}{l}2x=\frac49\\ 11x=3\end{array}\right.\Rightarrow\left[\begin{array}{l}x=\frac49:2=\frac29\\ x=\frac{3}{11}\end{array}\right.\)