Word Problems! Please Help

[shorty21432]

Word Problems! Someone? Please Help I'm desperate and clueless

F varies jointly as A and T and inversely as the square of B. Determine F when K=3 A=4 T=6 and B=2

then theres,

Q varies directly as the square root of A and inversely as C. Determine Q when K=6/5, A=25 and C=3

I mean really this is all a different language to me. I'm not even gonna write the other 2 on here because I'm thinking I won't get many responses on this. I hate it when I miss class I get so lost! I hope I can get some help

 

[srmichael]

F varies jointly as A and T and inversely as the square of B. Determine F when K=3 A=4 T=6 and B=2

then theres,

Q varies directly as the square root of A and inversely as C. Determine Q when K=6/5, A=25 and C=3

I mean really this is all a different language to me. I'm not even gonna write the other 2 on here because I'm thinking I won't get many responses on this. I hate it when I miss class I get so lost! I hope I can get some help

Basically, these problems are attempting to tell you how one variable behaves based on its relationship to other variables (proportion, if you will). For these problems, there is always a proportionality constant (usually indicated by "k") which you must first solve for first if not provided to you. In your problems they give you "k", so you're good there. The problem will usually provide values that you can plug in to solve for "k" if "k" is not provided.

You will typically hear one of three relationship words in these problems:

1) Directly = one variable behaves the same as another variable. General form of equation is \(\displaystyle y=k(x)\) (y varies directly as x)

2) Jointly = like directly but with more than one variable. General form of equation is \(\displaystyle y=k(xw)\) (y varies jointly as x and w)

3) Inversely = one variable behaves reciprocally as another variable. General form of equation is \(\displaystyle y=\frac{k}{x}\) (y varies inversely as x)

So I will do the first problem and see if you can do the second and the others you may have.

\(\displaystyle \displaystyle F=K(\frac{AT}{B^2})\)

Now, just plug and chug:

\(\displaystyle \displaystyle F=3(\frac{4\cdot 6}{2^2})\)

\(\displaystyle \displaystyle F=3(\frac{24}{4})\)

\(\displaystyle \displaystyle F=3(6)\)

\(\displaystyle \displaystyle F=18\)