Friday, April 16, 2010

Basic Algebra



11X + 23 = 4X - 5

That ↑ is called an equation.

My job is to find out the mystery number X.

First I get all the X's on one side.

So I subtract 4X from both sides of the equation.

11X + 23 - 4X = 4X - 5 - 4X

7X + 23 = -5


Next I subtract 23 from both sides.

7X + 23 - 23 = -5 - 23

7X = -28


Now I need to turn the 7 into an invisible 1.

So we divide both sides by 7.

7X / 7 = -28 / 7

X = -4


Let's check our answer.

11·-4 + 23 = 4·-4 - 5

-44 + 23 = -16 - 5

-21 = -21

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