Point A and B lie on the curve y=x^2-4x+7. Point A has coordinates (4,7) and B is the stationary point of the curve. The equation of a line L is y=mx-2 Where m is a constant. In the case where L passes through the midpoint of AB find the value of m?

3 Answers
May 8, 2018

7/3.

Explanation:

At the stationary point, dy/dx=0.

:. d/dx{x^2-4x+7}=0.

:. 2x-4=0.

:. x=2.

The corresponding y=x^2-4x+7=2^2-4xx2+7=3.

:. B=B(2,3).

Given that, A=A(4,7).

:." The mid-point "M" of "AB" is, given by, "

M=M((2+4)/2,(3+7)/2)=M(3,5).

because, M in L : y=mx-2, :., 5=m(3)-2," giving,"

m=7/3.

Enjoy Maths.!

May 8, 2018

m = 7/3

Explanation:

The function will have a stationary point when dy/dx = 0.

dy/dx= 2x - 4

So

0 = 2x -4 -> 4 = 2x -> x = 2

The corresponding value of y is y = 2^2 - 4(2) + 7 = 3

We now must find the midpoint between (2, 3) and (4, 7).

M = ((2 + 4)/2, (3 + 7)/2) = (3, 5)

We can now effectively solve for m:

5 = 3m - 2

m = 7/3

Hopefully this helps!

May 8, 2018

m = 7/3

Explanation:

To find the stationary point, B, we must compute the first derivative:

y' = 2x-4

We can find the x-coordinate of the stationary point, B, by setting the first derivative equal to 0 and the solving for x:

0 = 2x-4

2x=4

x = 2

Find the corresponding y value by evaluating the function at x = 2:

y = 2^2-4(2) + 7

y = 3

Point B = (2,3)

The midpoint between (4,7) and (2,3) is:

((4+2)/2,(7+3)/2) = (3,5)

Substitute the point (3,5) into the line y = mx-2 and solve for m:

5=m(3)-2

7 = 3m

m = 7/3