18 + 1 3 P1 for process to find common second differences n2 P1 for as part of an algebraic expression n2 A1 oe 19 = = 90° (given) 3 C1 one correct relevant statement CAD ACB = (common) C1 all correct relevant statements ABC ABD = 180 90 C1 correct conclusion with reasons ADC ABD – – = 180 90 ABC – – = BAC is similar to ABD CBA (AAA) 20 = 3, = 3 5 M1 for (2y 3)2 + = 18 x y y2 – = 4.2, M1 for expansion of bracket: e.g. 4y2 6y 6y + 9 x − – – = 0.6 y − M1 for quadratic ready for solving, e.g. 5y2 12y 9 = 0 – – M1 for factorising, e.g. (5y + 3)(y 3) = 0 oe – A1 for = 3, = 3 and = = x y x y –4.2, –0.6
18 n2 + 1 3 P1 for process to find common second differences P1 for n2 as part of an algebraic expression A1 oe 19 CAD = ACB = 90° (given) ABC = ABD (common) ADC = 180 – 90 – ABD = 180 – 90 – ABC = BAC ABD is similar to CBA (AAA) 3 C1 one correct relevant statement C1 all correct relevant statements C1 correct conclusion with reasons 20 x = 3, y = 3 x = − 4.2, y = − 0.6 5 M1 for (2y – 3)2 + y2 = 18 M1 for expansion of bracket: e.g. 4y2 – 6y – 6y + 9 M1 for quadratic ready for solving, e.g. 5y2 – 12y – 9 = 0 M1 for factorising, e.g. (5y + 3)(y – 3) = 0 oe A1 for x = 3, y = 3 and x = –4.2, y = –0.6
17745_08b_mock_papers_set_1_-_paper_1h_mark_scheme.docx