1questions in which sum of the series is give n v have to find the series
it is more appropriate to use
a-3d, a-d, a+d, a+3d
over
a, a+d, a+2, a+3d
same with a-d, a, a+d over a, a+d, a+2d
In which type of questions, is it more useful to take
a-3d, a-d, a+d, a+3d
over
a, a+d, a+2, a+3d
same with a-d, a, a+d over a, a+d, a+2d
same with a/r, a, ar or a/r3, a/r, ar, ar3
Not a thing that is out of the world but I think all those who have just started studying AP GP should have this perspective!
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4 Answers
11in case of maximizin or minimizin the series also........v can use
a-3d, a-d, a+d, a+3d
over
a, a+d, a+2, a+3d
same with a-d, a, a+d over a, a+d, a+2d
same with a/r, a, ar or a/r3, a/r, ar, ar3
3if we know the sum of the four consecutive terms of an A.P then it will be better to take a-3d ,a-d,a+d,a+3d since we know the value of a./r2
similarly if we know product of the four terms in a g.p
it is better to take a/r3,a/r,ar,ar3
62there is just a slight bit more too..
you also use a-3d, a-d, a+d , a+3d when you have product of these because you get no term of the form a^3 or ad^3 which makes life a bit more simple.