Math Homework Help!

[kk8273]

Can someone help me with my son's homework?

3f-12=3(f-12)

What is f?

Please help!!!!

Thanks!!!

 

[vicki_c]

4 I thought, until I wrote it out. And at first glance, it didn't look like a problem to solve as much as I thought an explanation of the distributive property or something. So I'm posting just so I can see how someone smarter answers the question!

At first I thought it was like this:

3f-12 = 3(f-12)
multiply the items in parentheses by the 3
3f-12 = 3f - 36
(I should note here that this already doesn't make any sense to me and that's why I know my answer must be wrong, because how can something minus 12 be the same as something minus 36)

add the 12 to both sides
3f = 3f - 24

Put the 3fs on the same side
0f = -24

That looked like an oops, so then I thought it was
2(3f) = -24
6f = -24
f = -4

So I'll just be checking back to see what the right answer is! I also stink @ math, so sorry I'm not really helping here.

 

[DISdreamin']

I got to the same place as vicki c and couldn't get any further. I'll be checking back too to see what you math whiz peeps come up with!

 

[tasha99]

3f-12= 3 (f-12)
3f-12 = 3f-36 taking out the parenthesis

-12= -36 subtract 3f from each side

which is untrue, so I think the answer is:

No solution

 

[vicki_c]

Maybe there is no answer. I Googled:

http://www.mathisfunforum.com/viewtopic.php?id=8582

 

[ancestry]

There is no answer to this problem.

If you enter the problem into google you will see that this is an inconsisent/false equation with no solution. No value for f will make this equation true.

 

[VirataMama4]

OP, is it possible for there not to be a solution?

Here is what both DH and I got:

3f-12=3(f-12)
3f-12=3f-36
+12 +12
= 3f=3f-24
-3f -3f
=0f= -24

Would love to know what the correct answer is!

 

[kk8273]

thanks so much for everyones help!!! I guess the answer is "no solution" which makes sense.

Thanks!!! And my son thanks you too!!

 

[NateNLogansDad]

OP, is it possible for there not to be a solution?

Here is what both DH and I got:

3f-12=3(f-12)
3f-12=3f-36
+12 +12
= 3f=3f-24
-3f -3f
=0f= -24

Would love to know what the correct answer is!

Perfectly written

 

[unionville]

high school math teacher here - the answer is "no solution"

 

[VirataMama4]

Perfectly written

Thanks! It helps that DD13 just went through Algebra 1 last year, so its kinda still fresh in our minds.

 

[turtlegirl25]

As a math teacher I this. Talk about collaboration.

 

[Cheshire Figment]

But then, of course, you can substitute

a = b
a^2 = a*b
a^2-b^2 = a*b-b^2
(a+b)(a-b) = b(a-b)
(a+b) = b
a+a = a
2a = a
2=1

Which can prove that 1=2.

 

[DISdreamin']

But then, of course, you can substitute

a = b
a^2 = a*b
a^2-b^2 = a*b-b^2
(a+b)(a-b) = b(a-b)
(a+b) = b
a+a = a
2a = a
2=1

Which can prove that 1=2.

When you divide by (a-b) aren't you essentially dividing by zero, since a=b?

 

[kamik86]

When you divide by (a-b) aren't you essentially dividing by zero, since a=b?

I think that is the point. this is actually an example used to show students why they can't divide by variables (or if they do must provide the assumption that the variable is not equal to 0) because if you don't you can prove that 1=2.

 

[Mandy_in_NC]

Letters do not belong in math!! Math is numbers. That is all I have to say about that. Can you tell I watched Forrest Gump over the weekend?

 

[SandrA9810]

As long as f is considered a variable, but if you get into "functions"... that's a different story.

 

[threecrazykids]

Letters do not belong in math!! Math is numbers. That is all I have to say about that. Can you tell I watched Forrest Gump over the weekend?

I agree completely!

I am HORRIBLE at math...however, I don't feel that it really matters in the "big picture" for me anyway, because not ONCE since I completed my last math class have I EVER ran into a situation where I needed to utilize any math problem beyond the simple calculations of the following:

addition
subtraction
multiplication
division

But I truly admire anyone who looks at a math problem that has any part of the alphabet in it and says "oooh cool, let's figure this one out"!

Not me...I just walk away, quickly.