Moderate -0.3 This is a standard discriminant problem requiring students to apply the condition b² - 4ac = 0 for equal roots, then solve the resulting quadratic equation in k. It's slightly easier than average because it follows a well-practiced procedure with no conceptual surprises, though algebraic manipulation requires care.
Question 7:
7 | Clearly states that
equal roots b2 4ac0 | AO2.4 | B1 | b24ac0for equal roots
k24(2k3)(k1)0
7k2 20k120
6
k ,k 2
7
Forms quadratic expression in k
(allow one error) | AO1.1a | M1
Obtains correct quadratic equation in k
(PI by correct values for k) | AO1.1b | A1
Obtains correct values for k for ‘their’
quadratic equation | AO1.1b | A1F
Total | 4
Q | Marking Instructions | AO | Marks | Typical Solution