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Originally Posted by catquery ur answer is right but i did it in different way
if we take ath term as -1 then a times ath term will be -1*-1=1 similarly
if we take bth term as 1 then b times bth term will be 1*1=1
a times ath term=b times bth term i.e. 1 but
(a+b)th term will be = -1+1 = 0 as a = -1 and b = 1
tell me whether i am right or wrong |
Seems to me like you are assuming too many things. There may be question which wil lead you in traps if you work out with such trivial exaples.
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Originally Posted by catquery one more question
a number 20 is divided into four parts that are in AP such that the product of the first and fourth is to the product of the second and third is 2:3. Find the largest part.
(a) 12 (b) 4 (c) 8 (d) 9 |
//Writing convention : a2 = a^2 and 2a = 2*a
As there are four number in AP assume a-3d, a-d, a+d, a+3d
Sum = 20 => a=5
3*(a2 - 9d2) = 2*(a2-d2)
a2 = 25d2 => d=1, Largest number is a+3d = 8
Hint:
1) when you are given odd numbers of terms in AP assume a-2d, a-d , a, a +2d
2) when you are given even number of terms auusme a-5d, a-3d, a-d, a+d, a+3d, a+5d (rememer common difference is 2d)
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