11 (a) If x² + 4x - 3 = (x + a)² + b for all possible values of x, find a and b.

(b) If y = x² + 4x - 3 , state the minimum value of y, and the value of x at which this minimum occurs.

(c) Sketch the graph of y = x² + 4x - 3 .
Try to use your answer to part (a) to calculate the co-ordinates of all intersections with the axes.

An office supply company conducted a survey before marketing a new paper shredder designed for home use. in the survey, 80 % of the people who tried the shredder were satisfied with it. because of this high satisfaction rate, the company decided to market the new shredder. assume that 80 % of all people are satisfied with this shredder. during a certain month, 100 customers bought this shredder. find the probability that of these 100 customers, the number who are satisfied is 69 or fewer.