Find all functions f(x) such that f(2x+1)=4x2+14x+7.
The quadratic trinomials f(x) and g(x) are such that f′(x)g′(x)≥|f(x)|+|g(x)| for all real x. Prove that the product f(x)g(x) is equal to the square of some trinomial.
The expression ax2+bx+c is an exact fourth power for all integers x. Prove that a=b=0.