If the 7th of an ap is equal to 11 times the 11th term, find the 18th term

-33 or 33

Step-by-step explanation:

The seventh term of an AP is written as:

The eleventh term of an AP is written as:

If the 7th term is 11 times the 11th term, then;

Expand to get:

We must have a=-52 and d=5

Or

a=52 and d=-5

For the first case, the 18th term is :

For the second case,

the simplified form is

step-by-step explanation:

we want to simplify the expression,

let us change the middle bar to a normal division sign to obtain,

we multiply the first fraction by the reciprocal of the second fraction to obtain,

we factor to obtain,

we cancel the common factors to get,

we simplify to get,

the correct answer is b