Thread: Algebraic

Two multiplied by three more than a number is fourteen.




2(3) + x =14

Not sure if that is right

Originally Posted by Patience

Two multiplied by three more than a number is fourteen.




2(3) + x =14

Not sure if that is right

Again, your applying the multiplication to only one term of the sum.

Let the number be x. So 3 more than the number is x + 3, then we miltiply that by 2 and the result is 14.

So 2(x + 3) = 14 .............expand the brackets to get:
=> 2x + 6 = 14 ...............now we subtract 6 from both sides to get:
=> 2x = 14 - 6 = 8 ..........now we divide both sides by 2 to get:
=> x = 4

How about this one?

Thirty six is fourteen less than five times a number.


5(x-14)= 36

5x - 70 = 36 + 70 = 106

x = 21.2

Is that right?

Originally Posted by Patience

How about this one?

Thirty six is fourteen less than five times a number.


5(x-14)= 36

5x - 70 = 36 + 70 = 106

x = 21.2

Is that right?

Um, no, your previous method would be correct here.

5x - 14 = 36
=> 5x = 36 + 14
=> 5x = 50
=> x = 50/5 = 10

Here is how you approach a problem like this. You start by labeling your unknown number, then build from the inside out. That is, you look what operation operates directly on the number, and then you put that in brackets. Then do what the problem says happens to what's inside the brackets, and equate it as directed.

So in this problem, we called our number x. What is operating on x? Well, it says we have 5 times our number x. so i build to 5x. then it says we have 14 less than 5 times our number x, so i build to 5x - 14. then it says that is 36, so i build to 5x - 14 = 36

In our previous problem: Two multiplied by three more than a number is fourteen.

We call our number x. Then we see that we have three more than our number x, so we build up to x + 3. Then we see that we have 2 times three more than our number x, so we build to 2(x + 3). then the problem says that is 14, so we build to 2(x + 3) = 14

Do you understand?