Official Solution:If the sum of all \(x^n\), where \(x\) is a positive two-digit integer and \(n\) is an integer from 0 to 5 inclusive, equals \(k\), which of the following equals \(x^6\)?A. \(kx + 1\)
B. \(k(x - 1) + 1\)
C. \(k(x - 1) - 1\)
D. \(k(x - 2) + 1\)
E. \(k(x - 2) - 1\)
We are given that:
\(x^0 + x^1 + x^2 + x^3 + x^4 + x^5 = k\)
This simplifies to:
\(1 + x + x^2 + x^3 + x^4 + x^5 = k\)
Multiply both sides of the equation by \(x\):
\(x + x^2 + x^3 + x^4 + x^5 + x^6 = kx\)
Adjust the equation by adding and subtracting 1 from the left-hand side:
\(1 + x + x^2 + x^3 + x^4 + x^5 + x^6 - 1 = kx\)
Substitute \(1 + x + x^2 + x^3 + x^4 + x^5 = k\) back into our equation:
\(k + x^6 - 1 = kx\)
\(x^6 = kx - k + 1\)
\(x^6 = k(x - 1) + 1\)
Answer: B