Algebra
# Advanced Factorization

Evaluate $\frac{(167 ^2-165 ^2)(163 ^2-161 ^2)(159 ^2-157 ^2)}{166 \times 162 \times 158}.$

Evaluate $\sqrt{23 \times 24 \times 25 \times 26+1}.$

$\quad$ What is the real number $A$ that satisfies

$\frac{77 ^4+77 ^2+1}{77 ^2+77+1}=78 ^2-A?$

What is the value of $490000-\frac{490000 \times 490001+1}{490701}?$