Question

Вычислите:
1) 46^2-92•31+31^2
2) 38^2-17^2
_________
47^2-361

Answer 1

$\displaystyle \tt 1). \ 46^{2}-92\cdot31+31^{2}=46^{2}-2\cdot46\cdot31+31^{2}=(46-31)^{2}=15^{2}=225;$

$\displaystyle \tt 2). \ \frac{38^{2}-17^{2}}{47^{2}-361}=\frac{(38-17)(38+17)}{(47-19)(47+19)}=\frac{21\cdot55}{28\cdot66}=\frac{3\cdot5}{4\cdot6}=\frac{5}{8}=0,625$