a) \(38,7\times\left(38,7-x\right)=38,7\)

\(38,7-x=38,7:38,7\)

\(38,7-x=1\)

\(x=38,7-1\)

\(x=37,7\)

De phan b) co bi nham khong ban ^.^

\(\left(\frac{3}{4}\times x-0,54\right):\frac{2}{9}=\frac{3}{4}-0,48\)

\(\left(\frac{3}{4}\times x-0,54\right):\frac{2}{9}=0,27\)

       \(\left(\frac{3}{4}\times x-0,54\right)=0,27\times\frac{2}{9}\)

         \(\left(\frac{3}{4}\times x-0,54\right)=0,06\)

                              \(\frac{3}{4}\times x=0,06+0,54\)

                                \(\frac{3}{4}\times x=0,6\)

                                            \(x=0,6:\frac{3}{4}\)

                                             \(x=0,8\)

​(3/4 *x -0.54):2/9 = 3/4- 12/25

(3/4 *x- 27/50) :2/9 =27/100

3/4*x- 27/50 = 27/100* 2/9

3/4*x-27/50 = 3/50

3/4*x = 3/50+ 27/50

3/4*x =3/5

x= 3/5:3/4= 4/5

\(a,x.1,2+x.1,8=45\)

\(\Rightarrow x.\left(1,2+1,8\right)=45\)

\(x.3=45\)

\(x=45:3\)

\(x=15\)

a, x=15

b, x=12

bài 2 tổng hiệu nha

a)13x3x32,27+67,63x39

=39x32,27+67,63x39

=39x(32,27+67,63)

=39x100

=3900

b,= 1- [ 1/2 x 1/3 x1/4 x..... x 1/100 ]

=1/2 x 2/3 x 3/4 x .......x 99/100

= 1x2x3x......x99 / 2x3x4x...... x100 [ rút gọn ]

= 1/100

a) x=1

b) x=65

a) x=1

b) x=65

k nha

\(\left(\frac{1}{1.2}+\frac{1}{2.3}+\frac{1}{3.4}+...+\frac{1}{19.20}\right)\div x=\frac{9}{10}\)

\(\Rightarrow\left(1-\frac{1}{2}+\frac{1}{2}-\frac{1}{3}+\frac{1}{3}-\frac{1}{4}+...+\frac{1}{19}-\frac{1}{20}\right)\div x=\frac{9}{10}\)

\(\Rightarrow\left(1-\frac{1}{20}\right)\div x=\frac{9}{10}\)

\(\Rightarrow\frac{19}{20}\div x=\frac{9}{10}\Rightarrow x=\frac{19}{20}\div\frac{9}{10}=\frac{19.10}{20.9}=\frac{19}{18}\)

Vậy x = 19/18 

giúp với nhé mn

a)\(=\frac{1}{2}.\frac{2}{3}.\frac{3}{4}.\frac{4}{5}......\frac{99}{100}\)

\(=\frac{1.2.3.4.....99}{2.3.4.5.6.....100}\)

\(=\frac{1}{100}\)

b) Tương tự như câu a

Ra kết quả phần b là \(\frac{101}{2}\) đúng hông?

a, x + 1/2 = 3/2

        x = 3/2 - 1/2

        x = 1

b,  x * 2 + x = 100 * 3

 x * ( 2 + 1 ) = 300

           x * 3 = 300

                x = 300 : 3

                x = 100

a,x=1

b,x (2+1)=300

3x=300

x=100

3/4 * x + 1/2 * x -15 = 35

3/4 * x +1/2 * x = 35 + 15 

3/4 * x +1/2 * x = 50

x * ( 3/4 + 1/2 ) = 50

x * 5/4 = 50 

x = 50 : 5/4

x = 40

phan b mik ko nhap dc nen bn tu lm nha

a, \(\frac{3}{4}\times x+\frac{1}{2}\times x-15=35\)

\(x+x-15=\frac{3}{4}-\frac{1}{2}\)

\(x+x-15=\frac{2}{8}=\frac{1}{4}\)

\(x=35-15\)

\(x=20\)

Vậy \(x=\frac{1}{4}\)và \(x=20\)

b, Chịu