7 (a) x = √a2 + b2 (i) Calculate x when a = -0.73 and b = 1.84 . (ii) Express b in terms of x and a. (b) ABCD and PQRS are rectangles. AD = x cm and PS = (x + 5) cm. Each rectangle has an area of 17 cm^2. (i) Write down an expression for PQ in terms of x. (ii) AB is 3 cm longer than PQ. Form an equation in x and show that it simplifies to 3x^2 + 15x - 85 = 0 . (iii) Solve the equation 3x2 + 15x - 85 = 0 . Give your solutions correct to 3 significant figures. (iv) Find the perimeter of the rectangle PQRS.