1. The curved surface area of a cylinder is \(2π(y2−7y+12)\) and its radius is \((y−3)\). Find the height of the cylinder \((C.S.A. of cylinder = 2πrh)\).
2. The sum of the first \(n\) natural numbers is given by the expression \(\frac{n}{2}+n^2\). Factorise this expression
Answer variants:
\((y−4)\)
\(\frac{n}{2}(n+1)\)
\(\frac{n}{2}(n-1)\)
\((y+4)\)