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Help me pls...........​

Help me pls...........​-example-1
User Tobby
by
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1 Answer

18 votes
18 votes

Hello,

We need first to know what's a gradient. The Gradient (also called Slope) of a straight line shows how steep a straight line is.

But how do we find the slope (or Gradient) from two points ?

For exemple, let's find the gradient of the two points PQ...

Method

1. We need the coordinates of the point P, and the point Q :

P = (6 ; -11)

Q = (k ; -9)

2. The slope is the change in height divided by the change in horizontal distance.

In other words we :

a) subtract the x values

b) subtract the y values

c) divide

Application for PQ

subtract x values : xQ - xP = k - 6

subtract the y values : yQ - yP = -9 - (-11) = -9 + 11 = 2

divide : (k-6) / 2

That is the gradient of PQ.. Now let us find the gradient of PR

Application for PR

subtract x values : xR - xP = 2k - 6

subtract the y values : yR - yP = -3 - (-11) = -3 + 11 = 8

divide : (2k-6)/8

That is the gradient of PR.

We know that by assumption, gradient of PQ = gradient of PR, what is the value of k ? Well, we simply need to solve an equation here :

gradient of PQ = gradient of PR

(k-6) / 2 = (2k - 6) / 8

k-6 = (4k - 12)/8 (we have multiplied by 2 on each sides of the equation)

8k - 48 = 4k - 12 (we have multiplied by 8 on each sides of the equation)

8k - 4k = - 12 + 48

4k = 36

k = 36 / 4 = 9

So the value of k in order for the two gradients to be equals needs to be equal to 9

Good luck

User Aliasbody
by
2.7k points
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