goalsnr wrote:

x97agarwal wrote:

In the xy-plane, does the line with equation y=3x+2 contain (r,s)?

1. (3r+2-s)(4r+9-s)=0;

2. (4r-6-s)(3r+2-s)=0

S1. Tells you that (3r+2-s) = 0; s = 3r + 2

S2. Tells you that (3r+2-s) = 0; s = 3r + 2

so (3r+2-s) is the common value in both the equations and this satisfies the equation y = 3x + 2

IMO C

X97, Stat1 and 2 give the same info. I dont understand why C? Pls explain.

From S1. (3r+2-s) = 0 or (4r+9-s)=0

S2. (4r-6-s) = 0 or (3r+2-s)=0

Exaple: If xy = 0 then either x = 0 or y = 0 or x and y both = 0

Similarily:

Lets assume that (3r+2-s) is not = 0 and (4r-6-s) = 0 and (4r+9-s)=0

Now equate both these equations, (4r-6-s) = (4r+9-s), you will get 15 = 0, which is not possible

The only way the equation can have a solution is if (3r+2-s) = 0