Question

apasati pe poza si rezolvati va rog repedeee!​

Answer 1

 

$\displaystyle\bf\\6399=3^4\cdot79=81\cdot79\\x=2(1+2+3+4+...+80)-6399\\\\x=2\cdot\frac{80\cdot81}{2}-6399\\\\x=2\cdot40\cdot81-81\cdot79\\\\x=80\cdot81-81\cdot79\\\\x=81(80-79)\\\\x=81\cdot1\\\\x=81\\\\\boxed{\bf\sqrt{x}=\sqrt{81}=9}$

 

 

Answer 2

Explicație pas cu pas:

2(1+2+3+...+80)=(2x80x81)/2=6480

6480-6399=81 si √81=9