SOLUTION: I have two Questions. My first one is, How do you algebraically figure out if vales of x and y can be the same? For example, In this equation 12= 2x + 3y I can figure out throug

Algebra ->  Linear-equations -> SOLUTION: I have two Questions. My first one is, How do you algebraically figure out if vales of x and y can be the same? For example, In this equation 12= 2x + 3y I can figure out throug      Log On


   



Question 797005: I have two Questions. My first one is, How do you algebraically figure out if vales of x and y can be the same?
For example, In this equation 12= 2x + 3y I can figure out through guess and check that the number 2.4 can be used for x and y at the same time.
Now for my next question.
Say you have something like this:
24= 4x + 8y
How do I determine algebraically what values of y and x will make 24 equal to 0?
Thanks so much!

Answer by KMST(5328) About Me  (Show Source):
You can put this solution on YOUR website!
12=+2x+%2B+3y
If x=y, then I can substitute x for y and re-write the equation as
12=+2x+%2B+3x --> 12=5x --> 12%2F5=x --> x=2.4

If 24=+4x+%2B+8y , x and y are related by that equation, and we can find some of the infinite pairs of values (x,y) that satisfy that equation.
(Finding infinite pairs would take infinite time, and I only have a few minutes until my bedtime).
24 will never be 0, or anything other than 24.
However, maybe you are thinking of finding what value of x corresponds to y=0 for that equation, and what value of y corresponds to x=0 for that equation.

x=0-->24=+4%2A0%2B8y-->24=0%2B8y-->24=8y-->24%2F8=y-->y=3
So the pair (0,3), with x=0and y=3 satisfies the relation 24=+4x+%2B+8y

y=0-->24=4x%2B8%2A0-->24=4x%2B0-->24=4x-->24%2F4=x-->x=6
So the pair (6,0), with x=6 and y=0 satisfies the relation 24=+4x+%2B+8y

Those two data pairs, and the infinite pairs (x,y) that satisfy 24=+4x+%2B+8y can be graphed as
Equations like 12=+2x+%2B+3y and 24=+4x+%2B+8y are called linear equations and their graphs are straight line.

If an equation has an x, and/or a y, and the x and/or y are at most multiplied times numbers and added or subtracted (no exponents, no x or y in a denominator, no other fancy stuff), it is a linear equation.

blue%28x=-2%29, red%28y=sqrt%283%29%29, and green%28y=2x%2B1%29 are linear equations