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Operations and Algebraic Thinking 218-221

Course: Operations and Algebraic Thinking 218-221>Unit 5

Lesson 2: One-step equations intuition

Dividing both sides of an equation

Let's get a conceptual understanding of why one needs to divide both sides of an equation to solve for a variable. Created by Sal Khan.

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• could you take 2x from both sides to find what x is?
• in an equation such as 1/2x=3+17 you could turn it into x=6+34 if that's what you mean
• why is a balance there
• to show how an equation works with the example of an old fashioned scale.
If you keep the scale balanced, the equation is correct, but if one side is heavier than the other side, you would not have a true equation.
• why didn't you do it the old fashion way 3x=9 and solve by doing in inverse opperation
• because he want us to learn the concept.
• At he says that 1/3 of this total mass is equal to 1/3 of that total mass. If the unknown mass was 5x and not 3x would you have to multiply by 1/5? Or if it was 8x would you have to multiply by 1/8?
• Yes, or instead you could divide by 5 or 8. In fact the division sign came from fractions...
• how to solve quardratic formula
• If you have an equation that looks like, "x^2+2x+1", you can either factor it out or use the quadratic formula to solve. If you want to use the quadratic formula, a = 1 (because there is 1 x^2), b =2 (since there are 2 x's), and c = 1 (since it is 1). All you have to do is plug those into the quadratic formula and simplify.
(1 vote)
• In the video he named different ways to solve this problems, does anybody have any other ways to solve it? or there is only one way to solve it
• there is usually more than one way to solve a problem.
• At , wouldn't 3 of those small, yellow blocks equal 1 of those big, blue blocks?