Find the A.P. in which S (10) = 465 and 9 S(3) = 4 S(6)
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Question

Find the A.P. in which S (10) = 465 and 9 S(3) = 4 S(6)
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crashonce · Answer

@ikram002p @ganeshie8

perl · Answer

AP stands for arithmetic progression?

crashonce · Answer

yes

perl · Answer

here is a formula for sum of AP

perl · Answer

http://www.regentsprep.org/regents/math/algtrig/atp2/arithseq.htm

perl · Answer

that should get you started

crashonce · Answer

but i dont know how to go from there

perl · Answer

we use the formula
S(n) = n*(a1 + an) / 2

perl · Answer

so we are given S(10) = 465

perl · Answer

S(10) = 465
S(10) = 10 * (a1 + an) /2 

so 
465 = 10*(a1+an)/2

perl · Answer

the next thing it says 
9 S(3) = 4 S(6) , im assuming that means multiplication

perl · Answer

9*S(3) = 4* S(6)

perl · Answer

9 *  3 * (a1 + an)/2 = 4 * 6 (a1 +an)/2

perl · Answer

so far we have two equations 

465 = 10*(a1+an)/2 
9 * 3 * (a1 + an)/2 = 4 * 6 (a1 +an)/2 

we can solve a system of two linear equations in 2 unknowns

perl · Answer

wolfram says there is no solution, so we might be doing something wrong http://www.wolframalpha.com/input/?i=solve+465+%3D+10*%28a%2Bb%29%2F2%2C+9+*+3+*+%28a+%2B+b%29%2F2+%3D+4+*+6+%28a+%2Bb%29%2F2+

crashonce · Answer

yea

perl · Answer

can you upload your worksheet or take a screenshot

crashonce · Answer

Questions correct
cant take a screenshot