Algebrahard · Past Paper
Solve for x: 3^(x+2) + 3^-x = 10.
A0, -2
B1, -1
C2, -2
D0, 2
✓ Correct Answer: A — 0, -2
Let 3^x = y. 9y + 1/y = 10 → 9y^2 - 10y + 1 = 0 → (9y-1)(y-1) = 0. y=1 (x=0) or y=1/9 (x=-2).
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✓ Correct Answer: A — 0, -2
Let 3^x = y. 9y + 1/y = 10 → 9y^2 - 10y + 1 = 0 → (9y-1)(y-1) = 0. y=1 (x=0) or y=1/9 (x=-2).
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