y = -8x + 5
To obtain the equation we require a point on it and it's slope.
the slope m = dy/dx at x = 1
dy/dx = -2-6x
x = 1 then dy/dx = -2 -6 = -8
equation of line in form y - b = m(x-a) with m = -8 and (a,b)=(1,-3)
y + 3 = -8(x-1)
y + 3 =-8x + 8
⇒ y = -8x +5 is the equation of the tangent
