The discussion revolves around determining how many terms are needed in the arithmetic series 11 + 16 + 21 + 26... to exceed a sum of 450. The series has a common difference of 5.
Some participants have successfully solved the quadratic equation and confirmed their results, while others are still clarifying their understanding of the steps involved in the calculations. There is no explicit consensus on the method, but productive dialogue is occurring.
Participants are working under the constraints of a homework assignment, which may influence their approach and the need for verification against textbook solutions.
How do you go from 455=17n+5n2, which is correct,Daaniyaal said:Homework Statement
How many terms are needed in the series 11+16+21+26...+ to exceed 450
d=5
Homework Equations
Sn=n/2(2u1+(n-1)d)
The Attempt at a Solution
(455 because is term exceeding 450 by the d of 5)
455=n/2(22+5n-5)
455=17n+5n2
455/17=5n2
Calculator work,
but the answer I get is not 12. The textbook says the answer is 12 :(