a) ( 851 - 751 ) + ( 486 - 186 )

= 100 + 300

= 400

b) ( 0,3607 : 0,01 ) + 36,07 x 95 + 36,07 : 0,65 

= 36,07 + 36,07 x 95 + 36,07 : 0,65 

= 36,07 x ( 95 : 0, 65 )

= 36,07 x 95,35 

= 3439 , 2745

c) 1,4 x 317 + 1,4 x 352 + 331 x 1,4

= 1,4 x ( 317 + 352 + 331)

= 1,4 x 1000

= 1400

G = \(\dfrac{2}{1.2.3}\) + \(\dfrac{2}{2.3.4}\)+ \(\dfrac{2}{3.4.5}\)+....+\(\dfrac{2}{18.19.20}\)

G = \(\dfrac{1}{1.2}\) - \(\dfrac{1}{2.3}\) + \(\dfrac{1}{2.3}\) - \(\dfrac{1}{3.4}\)+ \(\dfrac{1}{3.4}\) - \(\dfrac{1}{4.5}\)+......+ \(\dfrac{1}{18.19}\) - \(\dfrac{1}{19.20}\)

G = \(\dfrac{1}{1.2}\) - \(\dfrac{1}{19.20}\)

G = \(\dfrac{1}{2}\) - \(\dfrac{1}{380}\)

G = 189/380

\(2x-\left(1\dfrac{1}{4}-3\dfrac{2}{3}-2\dfrac{1}{6}\right)=5\dfrac{3}{4}-9\dfrac{4}{5}-1\dfrac{1}{10}\\ 2x-\left(\dfrac{5}{4}-\dfrac{11}{3}-\dfrac{13}{6}\right)=\dfrac{23}{4}-\dfrac{49}{5}-\dfrac{11}{10}\\ 2x-\left(-\dfrac{55}{12}\right)=-\dfrac{103}{20}\\ 2x=-\dfrac{146}{15}\\ x=-\dfrac{73}{15}\)

\(2x-\left(1\dfrac{1}{4}-3\dfrac{2}{3}-2\dfrac{1}{6}\right)=5\dfrac{3}{4}-9\dfrac{4}{5}-1\dfrac{1}{10}\)

\(2x-\left(\dfrac{5}{4}-\dfrac{11}{3}-\dfrac{13}{6}\right)=\dfrac{23}{4}-\dfrac{49}{5}-\dfrac{11}{10}\)

\(2x-\left(\dfrac{15}{12}-\dfrac{44}{12}-\dfrac{26}{12}\right)=\dfrac{115}{20}-\dfrac{196}{20}-\dfrac{22}{20}\)

\(2x-\dfrac{-55}{12}=\dfrac{-103}{20}\)

           \(2x=\dfrac{-103}{20}+\dfrac{-55}{12}\)

           \(2x=\dfrac{-146}{15}\)

             \(x=\dfrac{-146}{15}:2\)

             \(x=\dfrac{-73}{15}\)

34.36  = (32+2)(38-2)

          = 32.38 - 32.2 + 38.2 - 4

        = 32.38 +2( 38-32) -4

        =32.38 + 2.6 -4

      =32.38 + 8 > 32.28 vậy 34.36 > 32.38

\(64\cdot4^x=4^5\)

\(64=4^5:4^x\)

\(64=4^{5-x}\)

\(4^{5-x}=4^3\)

\(\Rightarrow5-x=3\)

\(x=5-3\)

\(x=2\)

64 . 4x = 45

= 64 . 4^x = 1024

= 4^x = 1024 : 64

=  4^x = 16

=  4^x = 4² 

= x =  2

\(\left(2^7:2^5\right)-\left(-3^5:3^4\right)-3x=\left|-4\right|:\left(-2\right)^2-2022^0\)

\(2^2-\left(-3\right)-3x=4:4-1\\ 7-3x=0\\ 3x=7\\ x=\dfrac{7}{3}\)

Có cái nịt

Tổng đáy lớn và đáy nhỏ là: \(165\times2:6=55\left(m\right)\)

Đáy lớn miếng đất ban đầu là: \(55:\left(2+3\right)\times3=33\left(m\right)\)

Diện tích miếng đất hình chữ nhật sau khi mua là: \(33\times6=198\left(m^2\right)\)

Diện tích đất cần mua thêm là: \(198-165=33\left(m^2\right)\)

Số tiền mua thêm đất là: \(23\times33=759\) (triệu đồng)

4/9 . ( 5/7 + 2/5 ) - 4/9(-2/7 + 7/5 ) 

= 4/9 . [ ( 5/7 + 2/5 ) - ( -2/7 + 7/5 ) ]

= 4/9 . ( 39/35 - 39/35 ) 

= 4/9 . 0

= 0 

\(\dfrac{4}{9}.\left(\dfrac{5}{7}+\dfrac{2}{5}\right)-\dfrac{4}{9}\left(-\dfrac{2}{7}+\dfrac{7}{5}\right)\\ =\dfrac{4}{9}\left(\dfrac{5}{7}+\dfrac{2}{5}+\dfrac{2}{7}-\dfrac{7}{5}\right)\\ =\dfrac{4}{9}\left(\left(\dfrac{5}{7}+\dfrac{2}{7}\right)+\left(\dfrac{2}{5}-\dfrac{7}{5}\right)\right)\\ =\dfrac{4}{9}\left(1+\left(-1\right)\right)\\ =\dfrac{4}{9}.0=0\)

548

548..