Question

THE FIRST AND LAST TERM OF AP ARE 5&45.IF THE SUM OF ALL ITS TERM IS 400. FIND THE COMMON DIFFERENCE AN NO. OF TERMS ? ? ? ? ​

Answer 1

Answer:

First term, a=5

Last term, l=45

Common difference = d

Sum of AP of n terms = (n/2)(a+l)

Sum = 400

On substituting values of a & l,

We get, n=16

l=a+(n-1)d

On substituting values of a,l & n

We get, d= 8/3

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Step-by-step explanation:

Answer 2

a=5. , l = 45

sum= 400

sum= n/2 (a+ l)

400 = n/2(5+45)

800 =n ×50

n. = 800/50

n= 16

45 = 5 + 15d

15d= 45-5

15d= 40

d= 40/15

d= 8/3