thi tốt !!!

2x . 3 = 15 => x = \(\frac{15}{6}\)= 2,5

=> \(\frac{x+16}{9}=\frac{y-25}{16}=\frac{z+9}{25}\)

= \(\frac{\frac{15}{6}+16}{9}=\frac{18,5}{9}=\frac{37}{18}\)

=> y-25/16=37/18 => y-25=296/9 => y=521/9=57,(8)

=> z+9/25=37/18 => z+9=925/18 => z=925/18=51,3(8)

24.(5²+1)(5⁴+1).........(5¹⁶+1)

=(5²-1)(5²+1)(5⁴+1)........(5¹⁶+1)

=(5⁴-1)(5⁴+1).........(5¹⁶+1)

=(5⁸-1)(5⁸+1)(5¹⁶+1)

=(5¹⁶-1)(5¹⁶+1)

=5³²-1