How do you solve (x+4)3−8=x(x+5)(x+7)−5?
1 Answer
Jun 14, 2018
Multiply out and cancel down - most of the difficulty immediately disappears in this particular problem
Explanation:
Multiply it all out, recalling the binomial theorem:
Collect terms, noticing that the cubic and quadratic terms cancel:
So
Plotting the two sides of the equation to sanity check it isn't easily done by hand, but it's still nice to see them crossing only once:
graph{(y-((x+4)^3-8))(y-(x(x+5)(x+7)-5))=0 [-10, 5, -200, 500]}