Question

Find the sum of the 10 terms of AP 30,35,40....

Answer 1

Answer:S10= 75  ; subscribe to my youtube channel #smtuitions

Step-by-step explanation:

AP: 30 , 35 , 40 .....

a1=30 , a2=35 , a3=40

d=a2-a1

d=35-30

d=-5

Sn=n/2[2a+ (n-1)d ]

S10=10/2[2*30 + (10-1)*(-5)]

S10=5[60+9*(-5) ]

S10=5[60+(-45) ]

S10=5[60-45]

S10=5*15

S10=75

Answer 2

Answer:

S10=525

Step-by-step explanation:

a1 = 30

a2 = 35

d = a2-a1 = 35-30 = 5

an= a+(n-1)d

a10 = a+(10-1)5

a10 = 30+45

a10 =75

Now,

Sn= n/2(a+l)

S10=10/2(30+75)

S10=5×105

S10=525

Remember:

an= l (last term)

a10=last term