If z = 2 + √3 find the integers a and b such that az² + bz = 1 + √3.
- If z = 2 + √3 find the integers a and b such that az² + bz = 1 + √3.[5]
Mark scheme
Marking points from the official mark scheme (Oct/Nov 2017). The mark or mark type is shown in brackets.
- [B1] z² = 7+4√3; Accept 4+3+4√3
- [M1] a(7+4√3)+b(2+√3)=1+√3; Equate both √3 terms and constant terms to obtain two equations in a and b.
- [A1] 7a+2b=1; 4a+b=1; Both correct. Accept equation with a multiple of √3
- [M1] Attempt to solve a pair of linear simultaneous eqns to a = or b =; M1dep
- [A1] a =1 and b = -3
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