15 x 15 = 225

i) Đặt \(\frac{3}{5}x=\frac{2}{3}y=k\)

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

\(y=k:\frac{2}{3}=\frac{3}{2}k\)

\(\Rightarrow x^2-y^2=38\)

\(\Leftrightarrow\left(\frac{5}{3}k\right)^2-\left(\frac{3}{2}k\right)^2=38\)

\(\frac{25}{9}k^2\cdot\frac{9}{4}k^2=38\)

\(\frac{25}{4}k^4=38\)

\(k^4=\frac{152}{25}\)

\(k=\)

Rồi xong....tính ko ra.

15*15=225

8+1=9

1+8=9

9-8=1

9-1=8

7+2=9

2+7=9

9-7=2

9-2=7

6+3=9

3+6=9

9-6=3

9-3=6

5+4=9

4+5=9

9-5=4

9-4=5