Given that 2⁵ˣ × 4ʸ = 1/8, show that 5x + 2y = -3.
- (i)Given that 2⁵ˣ × 4ʸ = 1/8, show that 5x + 2y = -3.[3]
- (ii)Solve the simultaneous equations 2⁵ˣ × 4ʸ = 1/8 and 7ˣ × 49²ʸ = 1.[4]
Mark scheme
Marking points from the official mark scheme (May/June 2014). The mark or mark type is shown in brackets.
- [B1] (i) B1 for 2^{2y}
- [B1] (i) B1 for 2^{-3}
- [B1] (i) B1 for dealing with indices correctly to obtain given answer
- [B1] (ii) B1 for either 7^{4y} or 7^0 seen
- [B1] (ii) B1 for x + 4y = 0
- [M1] (ii) M1 for solution of their simultaneous equations, must both be linear
- [A1] (ii) Al for both, allow equivalent fractions only
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