What two numbers add to equal - 11 and multiply to equal 28?

What two numbers add to equal - 20 and multiply to equal 51?

What two numbers add to equal - 5 and multiply to equal - 36?

-4 + - 7 = - 11 4 * 7 = 28

-17 + - 3 = - 20 17 * 3 = 51

4 + - 9 = - 5 4 * - 9 = 36

The answer for first is - 4 and - 7 (-4 + - 7) = 11, - 4 x - 7 = 28

The answer to the second is - 17 and - 3 (-17+-3) = 20, - 17 x - 3 = 51

The answer to the third is - 9 and 4 (-9 + 4) = - 5, - 9 x 4 = - 36

The answer is obtained by hit and trial method and there are many other algebraic ways to solve this. Since it was a bit easy one, i thought to apply the hit and trial method.