5/7 + 4/9 = 73/63

4/5 - 2/3 = 2/15

9/11 + 3/8 = 105/88

16/25 - 2/5 = 6/25.

1/3+1/6

=3/6

=>1/2

=1/3 + 6/36 

= 12/36 + 6/36

= 18/36 = 1/2

=1/3 + 6/36 

= 12/36 + 6/36

= 18/36

= 1/2

13/15-(y.4/15-2/9).3/5=1/5

(y.4/15-2/9).3/5=13/15-1/5

(y.4/15-2/9).3/5=2/3

y.4/15-2/9=2/3:3/5

y.4/15-2/9=10/9

y.4/15=10/9+2/9

y.4/15=4/3

y=4/3:4/15

y=5

Những chỗ có dấu "." thì thay bằng dấu nhân

36/20+15/20= 51/20

7/9-6/9= 1/9

\(\dfrac{9}{5}+\dfrac{3}{4}=\dfrac{36}{20}+\dfrac{15}{20}=\dfrac{36+15}{20}=\dfrac{51}{20}\)

\(\dfrac{7}{9}-\dfrac{2}{3}=\dfrac{7}{9}-\dfrac{6}{9}=\dfrac{1}{9}\)

1.

7/15:(1/2-9/10xX)-1/6=13/6

=>7/15:(1/2-9/10xX)=13/6+1/6

=>7/16:(1/2-9/10xX)=7/3

=>1/2-9/10xX=7/16:7/3

=>1/2-9/10xX=3/16

=>9/10xX=1/2-3/16

=>9/10xX=5/16

=>X=5/16:9/10

=>X=25/72

Mik xin lỗi nha dấu_ mình định ghi là + nha

Giúp mình nhanh lên mình còn nộp bài

 2/3+3/4_4/5+12/9+48/15.

=2/3+3/4+4/5+4/3 +7/4+16/5

= 2/3+4/3+3/4+7/4+4/5+16/5

= 2+10/4+4

=6+5/2=17/2

5/6+1/6=1

3-32/35=73/35

gold dragon đây bn

5/6+3/8:9/4= 5/6 + 1/6= 6/6= 1

3-4/7x8/5= 3- 32/35= 3/1-32/35= 73/35

Ta có: 

\(4\left(1+5+5^2+...+5^9\right)=5\left(1+5+5^2+...+5^9\right)-\left(1+5+5^2+...+5^9\right)\)

\(=5+5^2+5^3+...+5^{10}-1-5-5^2-...-5^9\)

\(=5^{10}-1+\left(5-5\right)+\left(5^2-5^5\right)+..+\left(5^9-5^9\right)\)

\(=5^{10}-1\)

=> \(1+5+5^2+...+5^9=\frac{5^{10}-1}{4}\)

Tương tự: \(1+5+5^2+...+5^8=\frac{5^9-1}{4}\)

\(1+3+3^2+...+3^9=\frac{3^{10}-1}{2}\)

\(1+3+3^2+...+3^8=\frac{3^9-1}{2}\)

=> \(A=\frac{5^{10}-1}{5^9-1}>\frac{5^{10}-1}{5^9}=5-\frac{1}{5^9}>4;\)

\(B=\frac{3^{10}-1}{3^9-1}< \frac{3^{10}}{3^9-1}=3+\frac{3}{3^9-1}< 4;\)

=> A > B.