the electric posts along a straight road are 23 m apart. If there are 12 electric posts, whats is the distance from the first post to the lasts post?

so first, basically multiply the value of the first post which is 23m to 12 (total number of posts) and from that, we will get 276m.
Now, we are told to find the distance between the first post up to the last post.
Simply subtract 23 from 276, because we already have the value of 1 of the 12 posts.
Lastly, 276 subtracted by 23 is 253.
Therefore, the distance from the first post to the last post is 253m.

short method: 23×11= 253

*we can also use the formula for the arithmetic sequence: a↓n= a↓1 + (n-1) d

a↓n - serves as the last term/general term/nth term
a↓1 - is the first term of the given problem or the first value
d - is the common difference or the difference of any two consecutive terms in an aritgmetic sequence

to express those terms, simply substitute their values

a↓n= a↓1 + (n-1) d

a↓12= 23 + (12-1) 23

*a↓12 because the last term or value that we need to look for is 12.

*23 is the first term and the common difference since it is said that the electric posts along a straight road are 23m apart.

a↓n= a↓1 + (n-1) d

a↓12= 23 + (12-1) 23

a↓12= 23 + (11)(23)

a↓12= 23 + 253

a↓12= 276 - this is the value of the 12th term or 12th post.

*again, since we need to find the distance between the first and last post, we need to subtract the value of the first term by the value of the last term: (276-23 = 253)

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