Saved Bookmarks
| 1. |
Let `a_1, a_2,...,a_(10)`be in A.P. and `h_1, h_2,..., h_(10)`be in H.P. If `a_1=h_1=2` and `a_(10)=h_(10)=3,` then `a_4h_7`isA. 2B. 3C. 5D. 6 |
|
Answer» Correct Answer - D Let d be the common difference of the A.P. Then, `a_(10)=3rArra_(1)+9d=3rArr2+9d=3rArrd=(1)/(9)`. `:." "a_(4)=a_(1)+3d=2+(1)/(3)=(7)/(3)` Let D be the common difference of the A.P. `(1)/(h_(1)),(1)/(h_(2)), . . . .,(1)/(h_(10))`. Then, `h_(10)=3` `rArr" "(1)/(h_(10))=(1)/(3)` `rArr" "(1)/(h_(1))+9D=(1)/(3)rArr(1)/(2)+9D=(1)/(3)rArr9D=-(1)/(6)rArrD=-(1)/(54)` `:." "(1)/(h_(7))=(1)/(h_(1))+6D=(1)/(2)-(1)/(9)=(7)/(18)rArrh_(7)=(18)/(7)` Hence, `a_(4)h_(7)=(7)/(3)xx(18)/(7)=6`. |
|