Let Q(x)=a0+a1x+⋯+anxn be a polynomial with integer coefficients, and 0≤ai<3 for all 0≤i≤n.
Given that Q(3)=20+173, compute Q(2).
Official solution
1. Given the polynomial Q(x)=a0+a1x+a2x2+⋯+anxn with integer coefficients ai such that 0≤ai<3 for all 0≤i≤n, and Q(3)=20+173, we need to determine Q(2).
2. Since Q(3)=20+173, we can write: Q(3)=a0+a13+a2(3)2+⋯+an(3)n=20+173
3. Separate the polynomial into rational and irrational parts: a0+a2(3)2+a4(3)4+⋯=20 a13+a3(3)3+a5(3)5+⋯=173
4. Simplify the irrational part: a13+a333+a593+⋯=173 a1+3a3+9a5+⋯=17
5. Simplify the rational part: a0+a23+a49+⋯=20
6. Since 0≤ai<3, we need to find coefficients ai that satisfy these equations. We start with the irrational part: a1+3a3+9a5=17 Given the constraints, we can try a5=1, a3=2, and a1=2: 2+3⋅2+9⋅1=2+6+9=17
7. Now, for the rational part: a0+3a2+9a4=20 Given the constraints, we can try a4=2, a2=0, and a0=2: 2+3⋅0+9⋅2=2+0+18=20
8. Thus, the polynomial is: Q(x)=2+2x+0x2+2x3+2x4+x5
9. To find Q(2): Q(2)=2+2⋅2+0⋅22+2⋅23+2⋅24+25 Q(2)=2+4+0+16+32+32=86
The final answer is 86.
Source: NuminaMath-1.5,
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