4.7 Power Series A power series is an expression of the form 80 anxn = ao + a1 x + a2x² + an xn n=0 an terms is constant but x is averiable whose domain of real number. 1- if y = eax dny = . dxn yn where n-order derivative→ yn = an eax Example 1// if y = e²x find dy7 y7 27e2x=128e2x = = sin ax→ y = a” sin(ax + n Soltion/ 2. if y Example //if y = sin 3x find dy5 Solution //y5 = 35 sin (3x + 577) = 243 sin(3x + 5) π 3. if y = cos ax → y" = a" cos(ax + n −) 2