Request a call back

Join NOW to get access to exclusive study material for best results

CBSE Class 10 Answered

Arithmetic Progression
Asked by | 26 Feb, 2009, 04:35: PM
answered-by-expert Expert Answer

Let the first term be a and the common difference be d.

Remember that two find two unknown quantities, we must have two equations involving them, which we'll solve and get the answer.

the first seven terms are

a,a+d, a+2d...a+6d

So their sum= (7/2)[a+a+6d]=(7/2)[2a+6d]

So,

 according to question

(7/2)[2a+6d]=20

This gives us

7a+21d=20...(i)

The next seven terms are

a+7d,a+8d,...a+13d

these terms can be thought of as in A.P. with first terms as a+7d and common difference as d.

 

So their sum =  (7/2)[a+7d+a+13d]=17

This gives us

7a+70d=17..(ii)

Solving the two equations we get

the values of a and d.

 

Answered by | 27 Feb, 2009, 03:00: PM
CBSE 10 - Maths
Asked by sonawnerohan01 | 23 Mar, 2024, 12:25: PM
ANSWERED BY EXPERT ANSWERED BY EXPERT
CBSE 10 - Maths
Asked by pathakvaishnavi9139 | 23 Mar, 2024, 10:45: AM
ANSWERED BY EXPERT ANSWERED BY EXPERT
CBSE 10 - Maths
Asked by choudharyniki001 | 22 Mar, 2024, 08:49: AM
ANSWERED BY EXPERT ANSWERED BY EXPERT
CBSE 10 - Maths
Asked by vn3950372 | 18 Mar, 2024, 08:38: PM
ANSWERED BY EXPERT ANSWERED BY EXPERT
CBSE 10 - Maths
Asked by vestigevestige85 | 17 Mar, 2024, 09:44: PM
ANSWERED BY EXPERT ANSWERED BY EXPERT
CBSE 10 - Maths
Asked by suvarnaapkare | 15 Mar, 2024, 04:59: PM
ANSWERED BY EXPERT ANSWERED BY EXPERT
CBSE 10 - Maths
Asked by anubhutiupadhaya | 15 Mar, 2024, 03:33: PM
ANSWERED BY EXPERT ANSWERED BY EXPERT
Get Latest Study Material for Academic year 24-25 Click here
×