Hi,
Looking at this question, the explanation video offers 2 paths for a solution, a) algebraically, or b) choosing numbers / BD strategy. The video then continues to explain the problem using BD strategy only.
Can someone explain how this would be solved algebraically, if at all? Per my education, we have two equations and three unknown variable (x, y, xy) so I am unsure how this would work.
Perhaps using quadratics and then the quadratic formula?
Thanks!
It’s two equations in two unknowns, so you can solve for each unknown uniquely.
xy is a term involving x and y, so it isn’t particularly correct to call it another unknown. For instance, if i gave you the value of x and y then you’d be able to tell me the value of xy is. Unknowns are usually independent of other unknowns.
An obvious way to solve it is to express one variable in terms of the other using the first equation, then substitute that into the second equation.
Yeah, you might find it useful to invoke the quadratic formula
