Question

459/987 * (1/4 +1/12 - 1/3) - 2009/2010

-9/7- 5/7 *[(-2/3)²-1] : -5/9

tìm x 

a) (x - 7/18) - 15/27 = -10/27

b) (3 1/2 - 2x ) * 1 1/3 =7 1/3

 cuối năm học , lớp 6A có 3/5 số HS đạt loại giỏi, 30% số HS đạt loại khá , còn lại 5 HS trung bình. Hỏi 6A có bao nhiêu HS 

câu 3

cho A= 2010²⁰⁰¹+1/2010²⁰⁰²+1 , B = 2010²⁰¹⁰+1/2010²⁰¹¹+1

Answer 1

tính :

a)\(\frac{459}{987}\cdot\left(\frac{1}{4}+\frac{1}{12}-\frac{1}{3}\right)-\frac{2009}{2010}\)

\(=\frac{459}{987}\cdot\left(\frac{3}{12}+\frac{1}{12}-\frac{4}{12}\right)-\frac{2009}{2010}\)

\(=\frac{459}{987}\cdot0-\frac{2009}{2010}\)

\(=\frac{-2009}{2010}\)

b) \(\frac{-9}{7}-\frac{5}{7}\cdot\left[\left(\frac{-2}{3}\right)^2-1\right]\div\frac{-5}{9}\)

\(=\frac{-9}{7}-\frac{5}{7}\cdot\left[\frac{4}{9}-1\right]\div\frac{-5}{9}\)

\(=\frac{-9}{7}-\frac{5}{7}\cdot\frac{-5}{9}\div\frac{-5}{9}\)

\(=\frac{-9}{7}-\frac{5}{7}\)

\(=-2\)

tìm x:

a) \(\left(x-\frac{7}{18}\right)-\frac{15}{27}=\frac{-10}{27}\)

\(\left(x-\frac{7}{18}\right)=\frac{-10}{27}+\frac{15}{27}\)

\(\left(x-\frac{7}{18}\right)=\frac{5}{27}\)

\(x=\frac{5}{27}+\frac{7}{18}\)

\(\Rightarrow x=\frac{31}{54}\)

b) \(\left(3\frac{1}{2}-2x\right)\cdot\frac{11}{3}=7\frac{1}{3}\)

\(\left(\frac{7}{2}-2x\right)\cdot\frac{11}{3}=\frac{22}{3}\)

\(\left(\frac{7}{2}-2x\right)=\frac{22}{3}\div\frac{11}{3}\)

\(\left(\frac{7}{2}-2x\right)=2\)

\(2x=\frac{7}{2}-2\)

\(x=\frac{3}{2}\div2=\frac{3}{4}\)

\(\Rightarrow x=\frac{3}{4}\)