Помогите, умоляю))

Найти значение производной в точке х0

а) f (x) = 4x^2 + 6x+3, x0 = 1;

б) f (x) = x/1+x^2, x0=0

в) f (x) = (3x^2+1) (3x^2-1), х0 = 1;

г) f (x) = 2x·cosx, x0 = п/4

А) f' (x) = 4*2x+6=8x+6 f' (1) = 8*1+6=14

b) f' (x) = (x' * (1+x²) - x * (1+x²) ') / (1+x²) ²=1+x²-2x²) / (1+x²) ²=1-x²) / (1+x²) ²

f' (0) = 1-0²) / 1+0²=1

3) f (x) = 9x²-1 f' (x) = 18x f' (1) = 18*1=18

4) f' (x) = 2x'*cosx+2x * (cos x) ' = 2cos x+2x * (-sin x) = 2cos x-2x * sin x

f' (π/4) = 2cos π/4-2*π/4*sin π/4=2*√2/2-π/2*√2/2=√2-π√2/4