If u = [ a z -1 3 b], |lu|l₂ = 8, ab = 25 then (a + b)² = A 25 B 100 C 75 D 50 5) Suppose that ƒ (0.75) = f(0.25) = ß if the composite trapezoidal rule with n=2 gives the value 4 for f(x) dx and gives the value 3 with n=4 then ß = A4 B1 C 3 D 2