Question

px+qy =c and rx+sy=d and ps=rq then these simultaneous equations have _____________
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Answer 1

Answer:

If px+qy > rx+sy , and x<y where p,q,r,s,x and y are all positive real numbers, then which of the following must be true?

1. p-q>r-s

2. p+q>r+s

3. p>s

ANSWER

Given : x<y

p,q,r,s,x,y are all positive real numbers.

px+qy > rx+sy

==> x(p-r) > y(s-q)

Since given that x< y and all numbers are positive , the above equality will hold only if

p-r > s-q . Solving this we get:

p+q > r+s.

As for equations 1 and 3, they are not necessarily true, this can be proved by plugging in positive numbers in above equation.

Thus answer is B