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S=(1-2)+(3-4)+(5-6)+...+(199-200)
S=(-1)+(-1)+...+(-1)
S=(-1).100=-100
S=1+(2-3)+(-4+5)+...+(98-99)+(-100+101)
S=1+(-1)+1+..+(-1)+1
S=1+25.(-1)+25.1
S=1+(-25)+25
S=1+0
=1
\(-\frac{1}{2}+\frac{2}{3}-\frac{3}{4}+\frac{4}{5}\)
\(=\left(-\frac{1}{2}-\frac{3}{4}\right)+\left(\frac{2}{3}+\frac{4}{5}\right)\)
\(=\left(-\frac{2}{4}-\frac{3}{4}\right)+\left(\frac{10}{15}+\frac{12}{15}\right)\)
\(=\left(\frac{-2-3}{4}\right)+\left(\frac{10+12}{15}\right)\)
\(=\left(\frac{-5}{4}\right)+\left(\frac{22}{15}\right)\)
\(=\frac{-75}{60}+\frac{88}{60}\)
\(=\frac{-75+88}{60}\)
\(=\frac{13}{60}\)
Mình ghi rõ từng chi tiết rồi nha , chúc bạn học tốt !!!
5/6 - 7/4 .|-2x - 3/2| = 7/12
7/4 .|-2x - 3/2| = 5/6 - 7/12
7/4.|-2x - 3/2| = 1/4
|-2x- 3/2| = 1/4 : 7/4
|-2x - 3/2| = 1/7
\(\Rightarrow\orbr{\begin{cases}-2x-\frac{3}{2}=\frac{1}{7}\\-2x-\frac{3}{2}=-\frac{1}{7}\end{cases}}\Rightarrow\orbr{\begin{cases}-2x=\frac{23}{14}\\-2x=\frac{19}{14}\end{cases}}\Rightarrow\orbr{\begin{cases}x=-\frac{23}{28}\\x=-\frac{19}{28}\end{cases}}\)
\(0,5.\left[\frac{4}{3}.\left(-20\right)\right].0,75.\frac{8}{-35}\)
\(\frac{5}{10}.\left[\frac{4}{3}.\left(-20\right)\right].\frac{75}{100}.\frac{8}{-35}\)
\(=\frac{2}{5}.\left[\frac{4}{3}.\left(-20\right)\right].\frac{3}{4}.\frac{8}{-35}\)
\(=\left(\frac{4}{3}.\frac{3}{4}\right).\left[\frac{2}{5}.\frac{\left(-35\right)}{8}\right].\left(-20\right)\)
\(=1.\left(\frac{2}{1}.\frac{1}{4}\right).\left(-20\right)\)
\(=1.\frac{1}{2}.\left(-20\right)=-\frac{20}{2}=\frac{10}{1}=10\)
Mk ko chắc, bn tham khảo nha
\(\frac{7}{6}+\frac{5}{6}:5-\frac{3}{8}.\left(-3\right)^2\)
\(=\frac{7}{6}+\frac{5}{6}.\frac{1}{5}-\frac{3}{8}.9\)
\(=\frac{7}{6}+\frac{1}{6}-\frac{27}{8}\)
\(=\frac{8}{6}-\frac{27}{8}\)
\(=\frac{32}{24}-\frac{81}{24}\)
\(=\frac{-49}{24}\)
Chúc bạn học tốt !!!
\(\left(-\frac{15}{22}\div-\frac{5}{11}\right)\cdot\frac{2}{3}\)
\(=\left(-\frac{15}{22}\cdot-\frac{11}{5}\right)\cdot\frac{2}{3}\)
\(=-\frac{3}{2}\cdot\frac{2}{3}\)
\(=-1\)
Ta có GTTĐ luôn lớn hơn hoặc bằng 0, mà theo đề bài
=> +) x + y - 1 = 0
x + y = 1
=> +) x - y - 2 = 0
x - y = 2
Số x là : ( 2 + 1 ) : 2 = 3/2
Số y là : ( 2 - 1 ) : 2 = 1/2
Vậy,.........
1/4 + 1/3 : (2x - 1) = -5
=> 1/3 : (2x - 1) = -21/4
=> 2x - 1 = -63/4
=> 2x = -59/4
=> x = -59/8
\(\frac{1}{4}+\frac{1}{3}:\left(2x-1\right)=-5\)
\(\frac{1}{3}:\left(2x-1\right)=\left(-5\right)-\frac{1}{4}\)
\(\frac{1}{3}:\left(2x-1\right)=\frac{-21}{4}\)
\(2x-1=\frac{1}{3}:\frac{-21}{4}\)
\(2x-1=\frac{-4}{63}\)
\(2x=\frac{-4}{63}+1\)
\(2x=\frac{59}{63}\)
\(x=\frac{59}{63}:2\)
\(x=\frac{59}{126}\)
\(\frac{4}{3}B=-1+\frac{3}{4}-\left(\frac{3}{4}\right)^2+...+\left(\frac{3}{4}\right)^{99}\)
\(B=-\frac{3}{4}+\left(\frac{3}{4}\right)^2-\left(\frac{3}{4}\right)^3+...+\left(\frac{3}{4}\right)^{100}\)
\(\Rightarrow\)\(\frac{7}{3}B=-1+\left(\frac{3}{4}\right)^{100}\Rightarrow B=\frac{\left(\frac{3}{4}\right)^{100}-1}{\frac{7}{3}}=\frac{3\left[\left(\frac{3}{4}\right)^{100}-1\right]}{7}\)
Như vầy đủ gọn chưa bạn?