A curve has equation y = x^2 - 7x. P is a point on the curve, and the tangent to the curve at P has gradient 1. Work out the coordinates of P.

The gradient of the tangent at P (=1) will be equal to the gradient of the curve at point P (=1). The gradient at a point on a curve is given by dy/dx (the differential). First, differentiate the equation of the curve, and equate the differential to 1. Solve for x by rearranging the equation. Finally, plug this value of x into the equation for y, and solve for y. dy/dy = 2x - 7 = 1, 2x = 8, x = 4. Therefore, y = (4)^2 - 7*(4) = -12Thus, the coordinates of P are (4,-12)

ST

Related Further Mathematics GCSE answers

All answers ▸

f(x) = 2x^3+6x^2-18x+1. For which values of x is f(x) an increasing function?


What is the distance between two points with x-coordinates 4 and 8 on the straight line with the equation y=(3/4)x-2


To differentiate a simple equation: y= 4x^3 + 7x


In a chess club there are x boys and y girls. If ten more boys join and one more girl joins, there is an equal amount of boys and girls. Knowing that y = 2x+2, Calculate x and y. [4 marks]