Ask a Question
x

Choose Country Code

x

Direction

x

Ask a Question

  • Ask a Question
  • Scan a Question
  • Post MCQ
  • Note: File extension must be of jpg, jpeg, png, bmp format and file size must not exceed 5 MB
x

Ask a Question

x

Hire a Tutor

Answers and Solutions

What's Your Question?
Answer

Use Basic   Sn = n/2 (2a +(n-1)d)

S30 = 15 (2a+29d)  = 30a + 435d

S20 = 10 (2a+19d) = 20a + 190d

S10 = 5 (2a+9d) = 10a + 45d

3(S20- S10 ) = 3(10a + 145d ) = 30a + 435d   = S30

Answer
S30=3 (S20-S10) 30/2 (a+l)=3 (20/2-10/2)(a+l) 15 (a+l)=15 (a+l) 0=0 So LHS=RHS
Answer

S 30 = 15[2a+29d] =30a + 435d S20 = 10[2a+19d] and S10 = 5[2a+9d] S20-S10 = 10a+ 145d 3(S20-S10) = 30a+435d = S30  

Answer
We know that Sn = n/2[2a+(n-1)d] Thus S30=30/2[2a+(30-1)d] S30=15(2a+29d)=30a+435d Then S20=10(2a+19d) S10=5(2a+9d) Then acc. To qustn 3(S20-S10) 3[20a+190d-10a-45d] 3(10a+145d) 30a+435d Thus S30=3(S20-S10)
Answer

Sum of an AP with n terms starting with a and ending in a+(n-1)d=n/2[2a+(n-1)d]

From the above we get, S 30= 15[2a+29d], S20=10[2a+19d], S10=5[2a+9d]

S20-S10=20a+190d-10a-45d=10a+145d

3(S20-S10)=30a+435d=S30

 

Answer

S 30 = 15[2a+29d] =30a + 435 d and

S20 = 10[2a+19d] and S10 = 5[2a+9d]

S20-s10 = 10a+ 145d

3(S20-S10) = 30a+435d

= S30

 

Answer

Sn = n/2 [2a+(n-1)d] to find the sum of n terms of an AP Where a= First term d = difference

 S20 = 20/2 [2a+ (20-1)d] = 10[2a+19d] = 20a+190d. ------(1)

S10 = 10/2 [2a+ (10-1)d] = 5[2a+9d] = 10a+45d. ------(2)

S30 = 30/2 [2a+ (30-1)d] = 15[2a+29d] = 30a+435d. -----(3)

Eqn (1) - (2) gives S20 - S10 = (20a+190d) - (10a+45d) = 10a+145d 3(S20-S10) = 3(10a+145d) = 30a+435d = S30

Answer
Sn = n/2 [2a+(n-1)d] to find the sum of n terms of an AP Where a= First term d = difference Therefore S20 = 20/2 [2a+ (20-1)d] = 10[2a+19d] = 20a+190d. ------(1) S10 = 10/2 [2a+ (10-1)d] = 5[2a+9d] = 10a+45d. ------(2) S30 = 30/2 [2a+ (30-1)d] = 15[2a+29d] = 30a+435d. -----(3) Eqn (1) - (2) gives S20 - S10 = (20a+190d) - (10a+45d) = 10a+145d 3(S20-S10) = 3(10a+145d) = 30a+435d = S30 (ref eqn 3)

Post Answer and Earn Credit Points

Get 5 credit points for each correct answer. The best one gets 25 in all.

Post Answer