Integers a and b are such that (a + 3√5)² + a - b√5 = 51.
- (a)Find the possible values of a and the corresponding values of b.[6]
Mark scheme
Marking points from the official mark scheme (Oct/Nov 2014). The mark or mark type is shown in brackets.
- [B1] (a) (a+3√5)² = a² +3a√5+3a√5 + 45 oe. anywhere
- [B1] (a) Equate: a² + a +45=51
- [B1] (a) and 6a-b=0
- [M1] (a) (a+3)(a-2)=0. Attempt to solve three term quadratic with integer coefficients obtained by equating coeffs
- [A1] (a) a = -3, 2. Both as correct or one correct pair
- [A1] (a) b = -18, 12. Both bs correct
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