Question no 28

Question no 28 20. of in is •G

Dear Student,

Let the first term be a and common difference as d, hence the terms in the AP will be;

a, a+d, a+2d, a+3d.....

Where, nth term Tn=a+(n-1)d
since, a1+a3+a5=-12or, a+a+2d+a+4d=-12         as a3=a+2d, a5=a+4d by nth term formulaor, 3a+6d=-12or, a+2d=-4.....(i)Now, as a1a2a3=8or, a(a+d)(a+2d)=8or, a(a+d)(-4)=8            from (i) as a+2d=-4or, a2+ad=-2Putting the value of d from (i), we get a2+a(-4-a2)=-2or, 2a2+a(-4-a)=-2×2or, 2a2-4a-a2=-4or, a2-4a+4=0or, a-22=0or, a=2Putting the value of a in equation (i), we get,2+2d=-4or, 2d=-6or, d=-3



Hope this information will clear your doubts about the topic.

If you have any more doubts just ask here on the forum and our experts will try to help you out as soon as possible.


  • 0
What are you looking for?