9 (a) Factorise completely (ii) 9a^2-b^2 (b) Solve 7/3-m=4 (c) A right-angled triangle has a base that is 7 cm longer than its height, h cm. The hypotenuse of the triangle is 23 cm. (i) Show that h satisfies the equation (i) 4x^3-10xy, h^2+7h-240=0 (ii) Write down an expression, in terms of h, for the area of the triangle. (iii) Hence state the exact area of the triangle. (iv) Solve h^2+7h-240=0, giving your answers correct to 1 decimal place. (v) Calculate the perimeter of the triangle.