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## Algebra I (2018 edition)

### Unit 1: Lesson 5

Writing algebraic expressions introduction

# Writing expressions with variables & parentheses

Learn how to write algebraic expressions that involve grouping quantities in parentheses. Created by Sal Khan.

## Want to join the conversation?

• in the first problem why did he know to multiply -5+4x from the word product?
• at Salman says 4+(2*(7-2x)). Can't he just say 4+2(7-2x)?
• according to the PEMDAS order of operations,both will work :)
(1 vote)
• How would you write half of 14 in an algebraic expression
• To write anything as a fraction of itself (e.g. half of 14, one third of 6, e.t.c) , you will just need to multiply the number you're dividing by the numerator (e.g. half of 14 = 1/2*14=14/2=7)
• When you got the answer for the first question,shouldn't the answer be simplifies further to -34+32x? Why did you just leave it like that without simplifying. Wouldn't you get points off on a test or quiz grade?
• well, 34+ 32x is in simplest form, because you don't know the value of x.
• How would 7+ -2x be the same as 7- 2x ?
• For the last question, couldn't we have written the answer in this way 4+2(7-2x)?
(1 vote)
• The main reason that the parentheses were added is because of the word "quantity" which is an indication of grouping a set of terms together. You are correct that the parentheses are not needed and would do nothing if we expand this.
• how does 7+-2x==7-2x,how do we drop the + sign?
(1 vote)
• How do you type the dot symbol for multiplication?
(1 vote)
• On the keyboard, we use the * (shift-8 key) in place of the dot for multiplication.
• how do we do it if the letter is not x. Example: 12 more than 8.2 times a number n
(1 vote)
• It is the same procedure. But one change will make it different. Substitute n as x and follow the same steps you would usually do. Then, replace x as n and submit the answer.