but how with simultaneous equations do you get an answer of q e R
For this I used a bit of sense. I didn't do any matricies rubbish.
For the thing to have a unique solution they must not have the same gradient. So find the ratio of the components to see what value of p WOULD give the same gradient.
if they have the same gradient. IF they have the same gradient then we know that a unique solution doesn't exist. So then p can take any value but 15/4 and for q it doesn't matter. It can be anything.
For the second part, we imagine two lines parallel. If they are parallel they will never intersect, but as with part iii they can coincide for one value of q only, which will lead to infinite solutions.
So to answer ii, i answered iii first. If they lie on the same line they will share points. So I found that on the second equation, x = 5 when y = 0 so there is a point shared at (5,0)
Now we know that to have infinite solutions p must be fixed at 15/4 so -3(5) = q so q = -15 and p = 15/4 for infinite solutions.
In contrast and now to solve part ii, for there to be no solution they are parallel but cannot lie on the same line. Thus p must be 15/4 and q can take any value but -15.
All you guys have to do to solve these kinds of questions is use some visualisation and the methods become quite trivial. :smitten: