# Question Video: Finding the Unknown in a Problem Involving a Point Satisfying a Given Relation Mathematics • 8th Grade

Given that (π, 2π) satisfies the relation π₯ β 2π¦ = β3, find the value of π.

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### Video Transcript

Given that π, two π satisfies the relation π₯ minus two π¦ equals negative three, find the value of π.

So when we take a look at any pair of coordinates, what we can always say is that the first number or first coordinate is π₯ and the second coordinate is π¦. So therefore, in this question, weβve got our first coordinate is π. So, that means thatβs gonna be our π₯-coordinate. And our second coordinate is two π, so thatβs gonna be our π¦-coordinate.

So weβre told in this question that the coordinate pair π, two π satisfies the relation π₯ minus two π¦ equals negative three. So therefore, to solve, what we can do is substitute or sub π₯ equals π and π¦ equals two π into our equation, which is π₯ minus two π¦ equals negative three. And when we do that, what weβre gonna get is π, and thatβs because that was our π₯, minus and then weβve got two multiplied by two π. And thatβs cause we had two π¦ and π¦ equals two π. And then this is equal to negative three.

So therefore, what weβre gonna have is π minus four π equals negative three. Well, π minus four π is negative three π. So then, what weβve got is negative three π equals negative three. So then, if we divide both sides of the equation by negative three, and we want to do that cause we want to find out what single π is, well, when we do that, weβre gonna get π is equal to one. And thatβs because if we divide negative three by negative three, this is just one.

So, we can say that given that π, two π satisfies the relation π₯ minus two π¦ equals negative three, then the value of π is one.