Posted by TyTy on Saturday, January 5, 2008 at 5:34pm.
I'm not sure but if i cross multiply the two coordinates, i think the answer is...
x=-3?
Cross-multiplying seems to be the process:
http://www.jiskha.com/display.cgi?id=1199568727
So ...
-2/8 = x/12
8x = -24
x = -3
Right?
yes, x=-3
Although I am sure I will be called on the carpet for saying why, I will try anyway.
If it is a direct variation it is a straight line of form:
y = k x
put in your first point
8 = -2 x
so k = -4
NOW any other point on this line satisfies
y = -4 x
so put in 12 for y
12 = -4 x
x = -3 as you know from "cross multiplying"
yes, thats the way I didn't understand how to do before.
By the way, these problems are a special case of direct variation, linear.
The relation could be quadratic, cubic quartic ....
but is always of form y = k x^n
Here so far we are assuming that n = 1
Do you get it now?
Um, i did until you mention the linear part.
Fixing typo and expanding
y = k x
put in your first point
8 = -2 k
solve that for k
so k = -4
NOW any other point on this line satisfies
y = -4 x
so put in 12 for y
12 = -4 x
x = -3 as you know from "cross multiplying"
I do not think you will get direct variation that is quadratic etc in this course or they would have mentioned it. For now assume direct variation means y = k x
Ok , thank you for your help.
Related Questions
math - So I've been having trouble solving some problems. Mainly problems ...
Math - I asked this question yesterday, but I am still having alot of trouble, ...
Algebra - Find three ordered pairs (a,b) that satisfy the equation 3a - 5b = 9. ...
12th grade - I'm having trouble ordered triple in algebra 2 w/ trigonometry...
Pharmacy Math - I am having a lot of trouble with the pharmacy calculations is ...
English - I'm having a little bit of trouble with Adventures of Huckleberry ...
Psychology - This is for my psychology class. We're doing an experiment/...
quick algebra question - When asked what quadrant the coordinate (0,0) is in, ...
trigonometry - ---I asked this question Solve the following right triangles: a. ...
Algebra - Solve. 4t^3 + 11t^2 + 6t = 0 I am having a little trouble with this ...
For Further Reading
