About this video
Sal turns word statements into algebraic expressions. 'The sum of -7 and the quantity 8 times x' becomes -7 + 8x, 'take the quantity -3 times x and then add 1' becomes -3x + 1, and '-6 plus the product of -1 and x' becomes -6 + (-x), which is the same as -6 - x.
You'll be able to
- translate words like sum, product and quantity into algebra.
- write an expression like 8x for '8 times x'.
- explain why -6 + (-x) is the same as -6 - x.
Key words
- algebraic expression
- A maths phrase with numbers, variables and operations, like -7 + 8x.
- sum
- The result of adding.
- product
- The result of multiplying.
- quantity
- A group of terms treated as one thing, like 'the quantity 8 times x'.
- variable
- A letter, like x, that stands for a number.
Transcript
What I want to do in this video is write the algebraic expressions that represent the same thing that these statements are saying. So this first statement, they say the sum of negative 7 and the quantity 8 times x. So the sum-- so we're going to have an addition here-- of negative 7 and the quantity 8 times x.
So the quantity 8 times x, well, that's just 8x. So I can just write 8x over there. So it is negative 7 plus 8x. Or you could view this as the sum of negative 7 and the quantity 8 times x. Let's do the next one. Take the quantity negative 3 times x and then add 1.
So the quantity negative 3 times x, we can write that as negative 3x. And then we need to add 1 to that. So that's going to be plus 1. Now this one. Negative 6 plus-- so we can write negative 6 plus something-- the product of negative 1 and x. So the product of negative 1 and x, that's just going to be negative 1x, which is the same thing as negative x.
So we can write this as negative 6 plus negative x. Or we can just write this-- this is the exact same thing as negative 6 minus x. And we are done.
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