Tornikea
In the XY-coordinate plane, line A is defined by the equation j*x-y=-7 and line B is defined by the equation 3*x+2*y=k
If line A and line B are not parallel, at what point do they intersect?
(1) Line A passes through the point (3,1)
(2) Line B passes through the point (0,7)
Please follow the posting guidelines.
Given: A: y = jx+7, B : y = -1.5x+k/2
As A is NOT parallel to B ---> j \(\neq\)-1.5 ....(a)
Per statement 1, A passes through (3,1), without complete equation of B, we will not be able to solve this question. Not sufficient.
Check: solving the 2 equations y = -2x+7 and y = -1.5x+k/2, we get x = 14-k and y = 2k-21. Thus without the value 'k' we dont know the exact point of intersection.
Per statement 2, B passes through (0,7), thus 7 = 0+k/2 ---> k = 14. Thus, equation of B is y = -1.5x+7.
Solving for x, we get -1.5x+7=jx+7 ----> x(j+1.5) =0 ---> either x =0 or j=-1.5 but as per (a) above, j \(\neq\)-1.5
The only case possible is for x=0 ---> y =7 to be the actual point of intersection.
B is the correct answer.
Alternately, you can see that once you get the equations of A and B as
B: y = -1.5x+7
A: y = jx+7,
X-coordinate of intersection ----> -1.5x+7=jx+7 ---> x = 0. Put this value of x back into any 1 of the 2 equations, you will get y = 7 . Finally, note that the point of intersection is a constant/unique value
without 'j' or 'k'Hence B is sufficient to arrive at a unique answer.