Please answer this question I give brainliest thank you! Number 14

Math it's appreciated. (picture provided)

Which equation shows the quadratic formula used correctly to solve 5x2 + 3x -4 0 for x? cos -3+ v (3) 2-4() 2(5) 3+ |(3)² +4() 205) 3+ (3) 2-4() -3+ v (3)² +4()

What is the point of inflection for the function f(x)=2cos4x on the interval (0, pi/2)