Simplify F=NotA NotB (AB+Not B) using the rules of Boolean algebra.?

Why the bracket?

Does this mean it is and AND function?

Given a + b + c + d = 8 sq. the two factors (a + b + c + d)² = 8² a² + b² + c² + d² + 2ab + 2ac + 2ad + 2bc + 2bd + 2cd = sixty 4 a² + b² + c² + d² + 2(ab + ac + advert + bc + bd + cd) = sixty 4 a² + b² + c² + d² + 2(12) = sixty 4 a² + b² + c² + d² + 24 = sixty 4 a² + b² + c² + d² = 40 ........................ {{a million}} And given ab + ac + advert + bc + bd + cd = 12 ab + ac + bc + d(a + b + c) = 12 ........................... {{2}} From {{a million}}. The equation represents the sum of squares of all genuine numbers (so a² > 0, b² > 0, c² > 0, d² > 0), and our purpose that's to maximise the value of d. So assume a = b = c = 0 (to maximise d). even if from {{2}}, if a = b = c, LHS = 0 ? 12. subsequently our first assumption is fake. Now assume that a = b = 0, and c ? 0, (to decrease the type of words in {{2}} after simplified) The simplified equation of {{a million}} and {{2}}, given our 2nd assumption are c² + d² = 40 .................. {{3}} cd = 12 ...................... {{4}} From {{4}} c = 12/d replace c = 12/d into {{3}} (12/d)² + d² = 40 a hundred and forty four/d² + d² = 40 d? - 40d² + a hundred and forty four = 0 d² = 36, 4 (by using quadratic formulation) ==> the optimum value of d is 6 (with a = 0, b = 0, c = 12/6 = 2, values of a, b, c are interexchangeable) ok, my answer is misguided. = (