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### Course: Algebra (all content)>Unit 2

Lesson 12: Old school equations with Sal

# Linear equations 1

To solve linear equations, find the value of the variable that makes the equation true. Use the inverse of the number that multiplies the variable, and multiply or divide both sides by it. Simplify the result to get the variable value. Check your answer by plugging it back into the equation. Created by Sal Khan.

## Want to join the conversation?

• These comments are so old.
• ik gives me nostalgia
• Wait... I'm confused. I thought that linear equations involved coordinate planes and the slope of the line and that kind of stuff?
• no linear equation is only to figure out the value of variable
• why didn't you just multiply straight forward instead of simplifying...that just threw me off there?
Sorry i have the same question I just want to understand!!
• When you simplify, it's easier. You will still have to multiply in the end.

E.X.

10c = 20

To find c, you need to divide 20 by 10, but you could've done it before. It's still the same problem, but you can either simplify in the beginning or the end.
• I have a question about this problem that was given to me on my math homework. It seems like an easy problem but I don't understand it... could anyone help me? :)

Here's the question
Jennifer can make a pizza and sell it for \$10.She can also make cookies and sell them for \$3. Write an equation that
would show a combination of selling pizzas and cookies.
• P=\$10
c=\$3
\$10+\$3=\$13
• why didn't he just multiply but instead he simplified
• How does it work when you are simplifying two fractions with negative numbers?(diagonally)
Like this... -5/10 x -20/15. Does it work the same as it would with positive numbers?
• You can cancel diagonally when you have the PRODUCT of two fractions. When BOTH fractions are negative you are multiplying a negative by a negative and that gives you a positive - so the negatives cancel out.
• How do you do system of equations just in general i have an exam like elimanation
• For a system of equations, it usually best to use the linear combination(elimination) method. To do the elimination method line up the Xs Ys, and the normal number. You then would first see if you can add, or subtract or subtract to get rid of either X or Y. If you cant then multiply one of the equations so that you can. Then add, or subtract The rest should be pretty simple as it is just basic pre-algebra. Hope this helps, have a great day.
(1 vote)
• whats a improper fraction?