Solve the simultaneous equations log2(x + 4) = 2log2y, log2 (7y - x) = 4.
- Solve the simultaneous equations log2(x + 4) = 2log2y, log2 (7y - x) = 4.[5]
Mark scheme
Marking points from the official mark scheme (Oct/Nov 2017). The mark or mark type is shown in brackets.
- [B1] x + 4 = y²
- [B1] 7y-x=16; allow 2^4 for 16
- [M1] y² -7y+12 → (y-3)(y−4)(= 0) or x² -17x+60→(x-5)(x-12)(= 0); Attempt to eliminate x or y to obtain a three term quadratic.
- [M1] Solve a three term quadratic; M1dep
- [A1] → y = 3, x = 5 or y = 4 x=12; Allow for values seen even if correct pairs not clear.
Write your answer and get it marked
On Oracle Prep you can write or photograph your own answer and have it marked by AI against this mark scheme, with feedback on what you missed.
Sign up free →