Answer:
y=7x−5
Explanation:
We have; y=x4+2x2−x
First we differentiate wrt x;y=x4+2x2−x
∴dydx=4x3+4x-1
We now find the vale of the derivative at (1,2) (and it always worth a quick check to see that y=2 when x=1) we have dydx=4+4−1=7
So at the tangent passes through the coordinate (1,2) and has gradient m=7
We now use y−y1=m(x−x1) to get the equation of the tangent:
∴y−2=7(x−1)
∴y−2=7x−7
∴y=7x−5
