Question

the first term of an ap is 5 the last rerm is 45 and the summis 400 find the number of terms and cimmon difference​

Answer 1

Hey mate

QUESTION :- The first term of an ap is 5 the last Term is 45 and the sum is 400 find the number of terms and common difference​

Answer :

In an AP,

First term (a) = 5

Last term (l) = 45

Sum of the terms of the AP (Sn) = 400

Number of terms = (n) = ?

Common difference = (d) = ?

Now

Sn = n/2 × (a + l)

=> 400 = n/2 × (5 + 45)

=> n/2 × 50 = 400

=> n = (400 × 2)/50

=> n = 16

Again

l = a + (n - 1)d

=> 45 = 5 + (16 - 1) × d

=> 45 - 5 = 15 d

=> d = 40/15 = 8/3 (ANSWER)

                                                                                                                                         

Hope it helps you

Answer 2

Hey frnd here is ur answer---

GIVEN÷

a=5

l=45

Sn=400

Sn=n/2(a+l)

400=n/2(5+45)

800=50n

800/50=n

n=16..is the Number of terms..

l=a+(n-1)d

45=5+(16-1)d

45-5=15d

40=15d

40/15=d

8/3=d (common ratio)

Hope it's helps to u!!