5 + 5 + 5 + 5 +5 + 4 x 5^2 + 4 x 5^3 + 4 x 5^4 + 4 x 5^5 + 4 x 5^6 + 4 x 5^7 + 4 x 5^8 + 4 x 5^9 =	Pick: A) 5^20 B) 5^18 C) 5^14 D) 5^10 E) None of above
Let's see that 5 + 5 + 5 + 5 +5 is 5^2, then: 5^2 + 4 x 5^2 becomes 5 x 5^2 that is 5^3. You follow with the next element: 5^3 + 4 x 5^3 is equal to 5 x 5^3 that is 5^4. Then is assumed right before 4 x 5^9: 5^9 + 4 x 5^9 becomes 5 x 5^9 that is 5^10. Thus, the correct answer is the option 5^10, 5^10.
<result>D</result>
5 + 5 + 5 + 5 +5 + 4 x 5^2 + 4 x 5^3 + 4 x 5^4 + 4 x 5^5 + 4 x 5^6 + 4 x 5^7 + 4 x 5^8 + 4 x 5^9 =