Calculate s75 for the arithmetic sequence defined by

The value of is -675 and this can be determined by using the formula of the sum of n terms in the arithmetic sequence and the given data.

Given :

  --- (1)

The following steps can be used in order to determine the value of :

Step 1 - Substitute the value of (n = 1) in the expression (1).

Step 2 - Substitute the value of (n = 75) in the expression (1).

Step 3 - Now, the formula of sum in an arithmetic sequence is given below:

where n is the total number of terms, is the first term, and is the last term.

Step 4 - Substitute the values of the known terms in the above expression.

Step 5 - Simply the above expression.

For more information, refer to the link given below:

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The formula of a sum of an arithmetic sequence:

We have n = 75 and .

Calculate the first and seventy-fifth term:

Substitute:

the height of the surface increases from the center out to the sides of the road.

step-by-step explanation:

as we move out we move away from the x-axis.

and as mentioned in the problem statement that height of a road increases when we move away from the center x.

hence proved that 3rd option

the height of the surface increases from the center out to the sides of the road.

is the correct option.