Please check my maths?

posted by .

How should i do this question??

it says:

find the equation of the tangent to the curve y=(x-2)^3 at the point (3,1). calculate the coordinates of the point where this tangent meets the curve again.

I know how to get the first part, if i'm not wrong, it's y = 3x - 8

but no matter how i do, i cant get another point that is meeting the curve again!

This is what i did for the second part:

y=3x-8 ---- (1)
y=(x-2)^3 ----(2)

(x-2)^3 - 3x + 8 = 0
x^3 - 6x^2 + 9x = 0
x^2 - 6x + 9 = 0

I'm pretty sure i did something wrong...

  • Please check my maths? -

    your tangent equation is correct.

    also correct up to
    x^3 - 6x^2 + 9x = 0


    x(x^2 - 6x + 9) = 0
    x(x-3)(x-3) = 0

    so x = 0 or x = 3 (we knew that x=3 because we knew there was a tangent there)
    You lost the x=0, a very common error

    you can "lose" a constant if you factor it from a function f(x) = 0 but if you factor out a variable, that could be zero, thus a solution.

    so when x=0, y = -8, so the other point of contact is (0,-8)

  • my maths -


Respond to this Question

First Name
School Subject
Your Answer

Similar Questions

  1. calc

    for the parametric curve defined by x=3-2t^2 and y=5-2t ...sketch the curve using the parametric equation to plot of the point. use an arrow to indicate the direction of the curve for o<t<1. Find an equation for the line tangent …
  2. Calculus - Maths

    I got a few questions. Hope ya'll can help out. 1) for F(X) = 6x - 2x^2 Find the gradient of the chord joining the point where the X coorinates are 1 and (1+h) respectively. b) hence find the gradient at x=1 2) Find the Coordinates …
  3. math

    the tangent yo the curve y=x^2 +5x -2 @ the point (1,4)intersect the normal to the same curve @ the point (-3,-8) at the point P.Find the coordinates of point P.[ans: -1/3,-16/3] just give me some hint to calculate this solution.
  4. math

    find the coordinates of the point where the tangent to the curve y=x^3 +x +2 at the point (1,4) meets the curve again. [ans:-2,-8] pls help me i don't understand the question....
  5. calculus

    1. Given the curve a. Find an expression for the slope of the curve at any point (x, y) on the curve. b. Write an equation for the line tangent to the curve at the point (2, 1) c. Find the coordinates of all other points on this curve …
  6. calculus

    Consider the curve defined by 2y^3+6X^2(y)- 12x^2 +6y=1 . a. Show that dy/dx= (4x-2xy)/(x^2+y^2+1) b. Write an equation of each horizontal tangent line to the curve. c. The line through the origin with slope -1 is tangent to the curve …
  7. Maths

    I need some help with my maths questions please! What angle does the tangent to the curve y=x^4-x^3+7x make with the positive direction of the x-axis at the point where x=2?
  8. Calculus AB

    Sorry but I've got a lot of problems that I don't understand. 1) Let f(x)= (3x-1)e^x. For which value of x is the slope of the tangent line to f positive?
  9. Calculus AB

    Could someone please help me with these tangent line problems?
  10. Maths

    Point P in the curve y=x^3 has coordinates (3,27) and PQ is the tangent to the curve at P.Point Q touches the x-axis.Find the area of the region enclosed between the curve, PQ and the x-axis. My answer: I used differenttiation to find …

More Similar Questions