- #1
Daaniyaal
- 64
- 0
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 :(