PLLLZ HELP Find Sn if a1 = 20, d = –10, and n = 25.

–2500

–2750

2500

–5000

Option A: is the value of

Explanation:

It is given that the first term is

The common difference is

We need to determine the sum of 25 terms.

The sum of  terms of an arithmetic series can be determined using the formula,

Substituting , and

Thus, we have,

Simplifying the values, we get,

Subtracting the terms within the bracket, we get,

Multiplying the terms in the numerator, we have,

Dividing, we get,

Thus, the sum of the 25 terms is

Therefore, Option A is the correct answer.

12/11c

or

12

c

11

given that triangle abc is transformed two times to get triangle

a"b"c"

first abc is transformed in to a'b'c' as follows:

the coordinates of a are (1,-1) and transformed into a'(-1,1)

similarly b (4,-2) became b'(-4,2) and

c(7,-2) became c'(-7,2)

i.e. (x,y) becomes (-x,-y)

this is nothing but reflection about a point here origin.

thus first transformation is reflection on the origin.

next is exactly shifting 3 units down

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