Question

Algebra 1 help please!

Evaluate 9 - 3 • 2 + 4.

6

7

15

16

Answer 1

Recall your order of operations; multiplication has a higher precedence than addition or subtraction. Hence, this is the same as computing \(\large 9-(3\cdot 2)+4\); in other words, compute the product first and then combine everything else afterwards.

Can you take things from here? :-)

Answer 2

9 - 3 * 2 + 4

9 - 6 + 4

9 - 10

-1
That's what i keep getting

Answer 3

Whenever you have a combination of + and -, you combine then going from left to right. This is important because 9 - 6 + 4 is not the same as 9 - (6 + 4), which is what you're doing (technically, 9 - (6 + 4) = 9 - 6 - 4, which is different from what you want to simplify originally). You want to treat 9 - 6 + 4 as (9 - 6) + 4 and then simplify that result instead.

Does this clarify things? :-)

Answer 4

So then the answer would be seven?

Answer 5

That would be correct. :-)

Answer 6

Can you see if i did this right?

Answer 7

15 - 4 + (7 - 5)2 = __________.
I got 7

Answer 8

Just curious, is the last part supposed to read \((7-5)\cdot 2\) or \((7-5)^2\).?

Answer 9

Oh sorry ^2

Answer 10

Ok. We note that \((7-5)^2 = 2^2 = 4\). So it follows that \(15- 4 + (7-5)^2 = 15 - 4 + 4\). How should this simplify? Recall again that you want to start combining terms left to right. In other words, \(15 - 4 + 4 = (15-4)+4=\ldots\).

Answer 11

So it would end up being fifthteen again?

Answer 12

Yes, that's correct. Is this starting to make sense?

Answer 13

Could you look at just one more please?

Answer 14

Sure. :-)

Answer 15

Evaluate 7 - (-1).

6

-6

8

-8

Answer 16

I don't understand the extra symbols

Answer 17

Do you know what the negative of a negative number is? (In other words, is the negative of a negative number positive or negative?) That's the key to solving this problem.

Answer 18

Oh okay! So it's positive 6?

Answer 19

No, that isn't correct. :-/

One thing that may help you with this is knowing that a negative number is the same as it's positive counterpart times -1; for example, \(-7 = (-1)\cdot 7\). So if you have \(-(-7)\), it's the same thing as saying \(-(-7) = (-1)\cdot(-7) = (-1)^2\cdot 7 = 7\). Hence, saying something like \(2-(-7)\) is equivalent to saying \(2+7\). Keeping this in mind, what would \(-(-1)\) be and thus, what is \(6-(-1)\)?

Answer 20

Woops, that last statement should be \(7-(-1)\).

Answer 21

-6?

Answer 22

No. :-/

Let's take this step by step; in my example above, I showed you that \(-(-7)=7\). So what is \(-(-1)\)?

Answer 23

1

Answer 24

Correct. So then it follows that \(7-(-1) = 7 + 1\). So what's the answer now? :-)

Answer 25

8 :D

Answer 26

Correct. Does this make more sense now? :-)

Answer 27

Yeah, but if it isn't to much of a bother can we work on one more?

Answer 28

Sure, that's fine with me. :-)

Answer 29

Natalie made a mistake in the following problem.

The mistake was made in Line ___.


Line 1

6(4) ÷ 2 - 1 + 5

Line 2

6(4) ÷ 1 + 5

Line 3

24 ÷ 1 + 5

Line 4

24 + 5

Line 5

29

Answer 30

I think she made a mistake in like 2

Answer 31

That would be correct.

Answer 32

What's the mistake? :-)

Answer 33

cause when i tried to solve it i got 6

Answer 34

she forgot to multiply

Answer 35

That really isn't the mistake here. What changes from Line 1 to Line 2?

Answer 36

the 2

Answer 37

Yes. In particular she made the mistake thinking that \(6(4)\div 2 - 1 + 5 = 6(4)\div (2-1)+5\). Multiplication and division have higher precedence than addition and subtraction, so you need to simplify the multiplication and division first before doing any addition and subtraction.

Answer 38

Thank you for all your help!! Have fun with you medal, new testimonial and a new fan :)!!!!

Answer 39

It was a pleasure. I hope this order of operations business makes more sense now! :-)

Answer 40

Yes it does!