1.
Let (x+10)50+(x10)50=a0+a1x+a2x2++a50x50(x + 10)^{50} + (x - 10)^{50} = a_0 + a_1 x + a_2 x^2 + \dots + a_{50} x^{50}, for all xRx \in \mathbb{R}. Then a2a0\dfrac{a_2}{a_0} is equal to