Find the 25th term of the following sequence. 19, 13, 7, 1, -5, … -125 131 125 -131

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

source:

(5x-1)^2= (5x)^2-2(5x)×1+(1)^2=25x^2-10x+1