Find the value of the infinite nested radical expression: 20 − 20 − 20 − 20 − … \sqrt{20 - \sqrt{20 - \sqrt{20 - \sqrt{20 - \ldots}}}} 20 − 20 − 20 − ...

Find the value of *Y* from the system of equations: $$\begin{cases} X - 2Y + 2Z = 16 \\ X - Y + Z =...

If $x = 8 + \sqrt{5}$ and $y = 8 - \sqrt{5}$, then find the value of $x^2 + y^2$....

Simplify the expression $$\frac{a^{7} \times b^{8} \times c^{7}}{a^{9} \times b^{5} \times c^{4}}$$....

Simplify the expression $$(5z - 12y)^2 + (12z + 5y)^2 - 144z^2$$...

If $x = 4 + \sqrt{6}$ and $y = 4 - \sqrt{6}$, then find the value of $x^2 + y^2$....

Simplify the expression: $$(5z - 7y)^2 + (7z + 5y)^2 - 49z^2$$...