45 nha bạn

45 na bn ơi

   1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9

= ( 1 + 9 ) + ( 2 + 8 ) + ( 3 + 7 ) + ( 4 + 6 ) + 5 

= 10 + 10 + 10 + 10 + 5

= 45

\(\frac{1}{3}\cdot x+\frac{2}{5}\cdot\left(x-1\right)=4\)( Chú ý . là dấu nhân )

\(\frac{1}{3}\cdot x+\frac{2}{5}\cdot1+\frac{2}{5}\cdot x=4\)

\(\frac{1}{3}\cdot x+\frac{2}{5}+\frac{2}{5}\cdot x=4\)

\(\frac{2}{5}+x\cdot\left(\frac{1}{3}+\frac{2}{5}\right)=4\)

\(\frac{2}{5}+x\cdot\frac{11}{15}=4\)

\(x\cdot\frac{11}{15}=4-\frac{2}{5}\)

\(x\cdot\frac{11}{15}=\frac{18}{5}\)

\(x=\frac{18}{5}:\frac{11}{15}\)

\(x=\frac{54}{11}\)

Đoàn Thanh Phương làm sai rồi x phải = 6 mink lam được rồi

(1125 x 4) x 1/5 x 1/3 = 300

Ta có: 1125 x 4 = 4500

\(\frac{1}{5}\) của 1125 x 4 là: 4500 x \(\frac{1}{5}\) = 900

\(\frac{1}{3}\) của\(\frac{1}{5}\) của 1125 x 4 là: 900 x \(\frac{1}{3}\) = 300

BÀI NÀY LÀ BÀI NÂNG CAO NHÉ MỌI NGƯỜI :33

(1+19)+(2+18)+(3+17)+(4+16)+(5+15)+(6+14)+(7+13)+(8+12)+(9+11)+20

=20+20+20+20+20+20+20+20+20+20

=20x10

=200

=210

tk mình nha

Ta có : 1 + 2 + 3 + 4 +5 + 6 + 7 + 8 + 9 + 10 + 11 +  12 + 13 + 14+ 15 + 16 + 17 + 18 + 19 + 20

        = ( 1 + 20 ) + ( 2 + 19 ) + ( 3 + 18 ) +  ( 4 + 17 ) + ( 5 + 16 ) + ( 6 + 15 ) + ( 7 + 14 ) + ( 8 + 13 ) + ( 9 + 12 ) + ( 10 + 11 ) 

        =     21       +     21      +      21       +      21       +      21      +    21       +       21     +    21         +    21      +     21

                                ( có 10 số hạng 21 )

       =    21 x 10 = 210

\(\left(x+\dfrac{1}{3}\right)\times\dfrac{9}{14}\times\dfrac{7}{3}-\dfrac{1}{3}=1:\dfrac{9}{5}\\ \Rightarrow\left(x+\dfrac{1}{3}\right)\times\dfrac{3}{2}-\dfrac{1}{3}=\dfrac{5}{9}\\ \Rightarrow\left(x+\dfrac{1}{3}\right)\times\dfrac{3}{2}=\dfrac{5}{9}+\dfrac{1}{3}\\ \Rightarrow\left(x+\dfrac{1}{3}\right)\times\dfrac{3}{2}=\dfrac{8}{9}\\ \Rightarrow x+\dfrac{1}{3}=\dfrac{8}{9}:\dfrac{3}{2}\\ \Rightarrow x+\dfrac{1}{3}=\dfrac{16}{27}\\ \Rightarrow x=\dfrac{16}{27}-\dfrac{1}{3}\\ \Rightarrow x=\dfrac{7}{27}\)

A=\(\frac{2.6.10+6.10.14+...+194+198+202}{1.3.5+3.5.7+...+97.99.101}\)\(=\frac{2.2.2\left(1.3.5\right)+2.2.2\left(3.5.7\right)+...+2.2.2\left(97.99.101\right)}{1.3.5+3.5.7+...+97.99.101}\)

\(=\frac{2.2.2\left(1.3.5+3.5.7+...+97.99.101\right)}{1.3.5+3.5.7+...+97.99.101}\)\(=\frac{2.2.2}{1}=8\)

= 10 nhá cu 

1+2+3+4= 10

Chúc bn hok tốt

1+2+3+4=10

\(\left(x+1\right)+\left(x+2\right)+\left(x+3\right)+....+\left(x+100\right)=5070.\)

\(\left(x+x+x+x+....+x\right)+\left(1+2+3+....+100\right)=5070\)

\(100x+101.100:2=5070\)

\(100x+5050=5070\)

\(100x=5070-5050=20\)

\(x=20:100=\frac{20}{100}=\frac{2}{10}=\frac{1}{5}=0,2\)

0,2 nhé bạn

(x+1/3)^4 = 16 = 2^4

=> x + 1/3 = 2

x = 5/3

\(\left(x+\frac{1}{3}\right)^4=16\)

\(\Rightarrow\left(x+\frac{1}{3}\right)^4=2^4\)

\(\Rightarrow x+\frac{1}{3}=2\)

\(\Rightarrow x=2-\frac{1}{3}\)

\(\Rightarrow x=\frac{6}{3}-\frac{1}{3}\)

\(\Rightarrow x=\frac{5}{3}\)

\(x+\frac{1}{3}=16:4\)

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

\(x=4-\frac{1}{3}\)

\(x=\frac{11}{3}\)