Question
Evaluate $^{20}\text{C}_{5}+\sum\limits_\text{r=2}^5\ ^{25-\text{x}}\text{C}_4.$
Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.
$\frac{1}{x}+\frac{1}{y}=\frac{3}{2}, \quad \frac{1}{y}+\frac{1}{z}=\frac{5}{6}, \quad \frac{1}{z}+\frac{1}{x}=\frac{4}{3}$