Thread: Find equation of tangent..

Find the equation of the tangent to the curve f (x) = 2x^2 - 4x + 4 which is perpendicular to the line y = -1/4x + 4.

I worked it out but got it slightly wrong and I dont know what I did incorrectly.
Could someone please clarify?

So what I did was I said okay. The gradient for the tangent is m=4.
and f'(x)=4x-4 so if the m=4, then x would equal 0.
If x=0, y=4 when you sub x=0 into f(x).

so i put it into the formula and got:
y-4=4(x-0)
y=4x+4

The answer is 4x-4.

Maybe its just a silly mistake that I can't point out and maybe its not. Anyone like to point it out?

The gradient of the tangent is 4. So when .




When

Using the point-gradient form

Oh i get it now thanks!

Since its perpendicular to the line, the product of the gradients of the lines equals -1



So the gradient of the tangent is 4.

You know that , which is the gradient function.

The gradient equals 4 when

yeah. for some reason before your math equatoins didnt load on your last post thats why i was confused but thanks for the thorough explaination

No worries. Have a good one