Math help (basic to advanced)

[Big Nate]

So the y-intercept is 1995 and then you add the number of years to that and plug that number into your equation.

Such as in 1995-2999=1004 year difference.

n=19/20(1004)+31 n=984.8

 

[Workdawg]

It says you're supposed to use the graph to solve the equation...

Foor the equation:

the value attached to the variable (t) is the slope of the line, rise/run.
That means for every 19 points the line goes up, it goes over 20 in this case.
The 31 is the y-intercept, so that gives you a starting point. The first point should be (0,31), then you can go up 19 and over 20, giving you (20, 50).

Since you're looking for the year 2015, (which is 20 years from 1995, as Jay calculated), the point (20,50) is exactly what you're looking for. The year 2015, the y value (number of cat owners) = 50.

If the next calculated point didn't give you the exact answer, you'd have to use the formula as Jay did.

 

[dmention7]

So the y-intercept is 1995 and then you add the number of years to that and plug that number into your equation.

Such as in 1995-2999=1004 year difference.

n=19/20(1004)+31 n=984.8

lol... where did 2999 come from? You are looking at the year 2015. Otherwise what you posted is correct.

 

[Big Nate]

I just made it up to see if i could get the correct answer for a year not shown.

 

[Big Nate]

It says you're supposed to use the graph to solve the equation...

Foor the equation:

the value attached to the variable (t) is the slope of the line, rise/run.
That means for every 19 points the line goes up, it goes over 20 in this case.
The 31 is the y-intercept, so that gives you a starting point. The first point should be (0,31), then you can go up 19 and over 20, giving you (20, 50).

Since you're looking for the year 2015, (which is 20 years from 1995, as Jay calculated), the point (20,50) is exactly what you're looking for. The year 2015, the y value (number of cat owners) = 50.

If the next calculated point didn't give you the exact answer, you'd have to use the formula as Jay did.

So you say I should use the triangle method to solve the problem?

 

[Workdawg]

The problem says specifically to use the graph to solve the problem.

Assuming I described "the triangle method" then I guess so.

It's a good idea to know how to solve it as Jay suggested though, as that will always give an exact answer.

 

[Big Nate]

5(a + 3) = 7(a - 5) Solve Just a sanity check.

 

[dmention7]

5(a + 3) = 7 (a - 5)

5a + 15 = 7a - 35

15 + 35 = 7a - 5a

50 = 2a

a = 25

 

[Big Nate]

OK i got the same answer.


On this one how would I set up the equation? I will work it out I just need help setting it up.

Review A doctor prescribes an ointment that is 4% hydrocortisone. A pharmacist has 1% and 9% concentrations in stock. How many ounces of each should the pharmacist use to make a 4 ounce tube?

 

[dmention7]

If A is the ounces of 1% stock, and B is the ounces 9% stock, then you would set it up like this:

A * 0.01 + B * 0.09 = 4 * 0.04

That equation says that the total medicine from stock A + the total medicine from stock B is equal to the total medicine in 4 ounces of the final mixture.

Further, you know that you're making a total of 4 ounces, so A + B = 4, which you can rearrange to B = 4 - A

Now, since you can represent B in terms of A, you plug that into the original equation to get:

A * 0.01 + (4 - A) * 0.09 = 4 * 0.04

Make sense?

 

[Big Nate]

Jay that worked great.

In the end A=2.5

You would add 2.5 oz of 1%
and 1.5 oz of 9%
to get a 4 oz 4%

Thanks a lot guys for the help again.

 

[Big Nate]

I need to write this in interval notation.

 

[Z-licious]

multiply both sides by 10 so you get -x >= -120.

Now when you multiply by a negative number you have to flip the inequality, so multiply by -1 to get x <= 120

Now it's easy to see that X has to be anything from negative infinity to positive 120 to make the equation true.

(-infinity symbol, 120]

You use [ on the right side to denote that is it less than or equal to. If it were just less than, it would be:

(-infinity symbol, 120)

 

[dmention7]

oh snap! Azn takin charge of the math thread!

 

[Big Nate]

I think my big issue is with the basic algebra. I lose track of the negative signs and from there it all breaks down.

Here is another one that I am having trouble with.

 

[Workdawg]

Multiply by 3: y-6 = -15

ADD 6: y = -9

 

[Z-licious]

Dan beat me to it.

 

[Big Nate]

How about this, do I need to find a common denominator? and if so what do I do after I find that?

 

[Workdawg]

You don't need one, no... you'd only need it if you had to combine terms with different denoms... add, subtract, multiply or divide them... since you don't need to combine anything that doesn't have a different denom, you don't have.

Subtract 5/6: c/9 = -5/6 -5/6
Combine: c/9 = -10/6
Multiple by 9: c = (-10/6) * 9 = -90/6
Simplify: c = - 15

 

[Big Nate]

Here they are asking me to solve this by graphing.

I need the Y intercept