Let, f(x) = y = -12x^2+6x-8
Substitute x = -1 in f(x) we get y = -26
y = -12x^2+6x-8
Differentiate ‘y’ w.r.t ‘x’ we get
dy/dx = -24x+6
By putting value of ‘x’ we get
dy/dx = 30
Slope(m)=dy/dx = 30
Equation of tangent => (y - y1)=m(x - x1)
Here, x1= -1 and y1 = -26 and m = 30
So, (y - (-26)) =30(x - (-1))
y+26=30(x+1)
y+26=30x+30
30x - y + 4 =0 is the equation of tangent at x = -1
