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# Equation practice with segment addition

If we split a line segment into two segments, the length of the total segment equals the sums of the lengths of the two smaller segments. We can make an equation out of the given information. After we solve for the value of x, we can substitute that value back into the expression for the length we are seeking. Created by Sal Khan.

## Want to join the conversation?

• the captions said jfk lmao
• I agree with that.
• I like o know if monkes eat more than bannanas
• Wait, if I have a perpendicular set of lines and I needed to use this method to figure it out, how would I do that? I don't even know what it's called because I was late to starting school and I need help DX
• If you have two lines that are perpendicular, it means that they intersect each other at a 90-degree angle. One way to determine if two lines are perpendicular is by checking the slopes of the lines.

If the slopes of two lines are negative reciprocals of each other, then they are perpendicular. The negative reciprocal of a slope is found by flipping the fraction upside down and changing its sign. For example, the negative reciprocal of 2/3 is -3/2.

To use this method to determine if two lines are perpendicular, you need to find the slopes of the two lines, and then check if they are negative reciprocals of each other. If they are, then the lines are perpendicular.

For example, if you have two lines with slopes of 2 and -1/2, you can determine if they are perpendicular by finding the negative reciprocal of each slope.

The negative reciprocal of 2 is -1/2
The negative reciprocal of -1/2 is 2
Since the slopes of the two lines are negative reciprocals of each other, the lines are perpendicular.
(1 vote)
• Is there anyone on Khan Academy anymore? All these comments are from years ago. I see no active or recent questions. If I ask a question will it even get answered?
• There are plenty of people on Khan Academy. Sometimes users ask questions more often than other times.
• where does the subtracting 18 come from?
• To get x on one side of the equation so Sam subtracted 18 from each side because what you do to one side, you have to do to the other
• If JK+KL=114 () does that mean KL+JK also equals 114?
• Yes, because it doesn't matter which order things are added together in. (commutatative property of addition)