Write down and simplify the first \(4\) terms in the expansion by the binomial theorem of \(\left(1 - \tfrac{1}{2}x\right)^{10}\).

Find the coefficient of \(x^2\) in the expansion of \[ (5 + 4x)\left(1 - \tfrac{1}{2}x\right)^{10}. \]

Write down and simplify the first \(4\) terms in the expansion by the binomial theorem of \(\left(1 - \tfrac{1}{2}x\right)^{10}\).

Find the coefficient of \(x^2\) in the expansion of \[ (5 + 4x)\left(1 - \tfrac{1}{2}x\right)^{10}. \]