Which explorer rediscovered the great banks of canada, found first by the vikings?

John Cabot

Explanation:

The great banks are series of the underwater plateau of the newfound lands on the north American banks of the continental shelves and are largest fishing banks,  are a relatively shallow and 91 meters in depth and john Cabot was a navigator and explorers of the north America coasts and that of the Canada.

5×^2+20-15 or -(5x^2-20+15)

Well, a and b together would be negative. b alone would also be negative.