How would I solve for a?

Question

"Solve for a such that the above function is continuous from -infinity to +infinity"

I am struggling with this problem because a is only present in one of the parts of the function and if I set the above part of the function to -4, it is undefined.

Any help?

Answer 1

HINT: $$2x^3+9x^2+11x+28=(x+4)(2x^2+x+7)$$