Questions
If sum of four numbers in A.P. is 28 and product of two middle terms is 45, then product of the first and last terms is
detailed solution
Correct option is B
Let four numbers in A.P. bea−3d, a−d, a+d, a+3dWe are given 28=(a−3d)+(a−d)+(a+d)+(a+3d)=4a⇒ a=7Also, (a−d)(a+d)=45⇒ 49−d2=45⇒d=±2.Now, (a−3d)(a+3d)=a2−9d2=13Similar Questions
If and 1 are in A.P, then x is equal to
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