The algebraic form for the sum of first n terms of an arithmetic seque

1.	The algebraic form for the sum of first n terms of an arithmetic sequence is 2n2 + 8n. How many consecutive terms of the sequence from the first, are to be added to get 330 ?
Answer» S_n= 2n²+ 8n (Given) 330 = 2n² + 8n 2n² + 8n – 330 = 0 n² + 4n – 165 = 0 n² + 15n – 11n – 165 = 0 n(n + 15) – 11 (n + 15) = 0 (n + 15) (n – 11) = 0 If n + 15 = 0 ⇒ n = – 15 (terms are not negative) n – 11 = 0 ⇒ n = 11 ∴ Hence, total 11 term from starting to be added.

The algebraic form for the sum of first n terms of an arithmetic sequence is 2n2 + 8n. How many consecutive terms of the sequence from the first, are to be added to get 330 ?

Answer»

S_n= 2n²+ 8n (Given)

330 = 2n² + 8n

2n² + 8n – 330 = 0

n² + 4n – 165 = 0

n² + 15n – 11n – 165 = 0

n(n + 15) – 11 (n + 15) = 0

(n + 15) (n – 11) = 0

If n + 15 = 0 ⇒ n = – 15 (terms are not negative)

n – 11 = 0 ⇒ n = 11

∴ Hence, total 11 term from starting to be added.

Discussion

No Comment Found

Related InterviewSolutions

Explain the different phases of the formation of people's Republic of China on the basis of following hints. Hints :(i) Autocracy of Chiang Kai-Shek(ii) Mao Zedong(iii) People's Republic
Arrange the following events in chronological order. (a) Guruvayur Satyagraha (b) Nivarthana prakshobham(c) Temple Entry Proclamation in Travancore (d) Vaikom Satyagraha
According to Satyajit Ray, shooting a scene with an animal is a difficult task. He narrates one such experience in ‘Project Tiger’. Prepare a write-up, detailing the difficulties Ray faced in shooting the scene with a tiger for the film ‘Goopy Gyne Bagha Byne’.(Hints : Scene with a tiger-approaches Bharat Circus Company-tiger brought to the bamboo grove-difficult to control the tiger-tiger calms down-shoots the scene-too dark-retake)
Arrange columns B and C according to the items in column A.S. No.ABC(i)CataractInfectionDiet Containing Vitamin A(ii)GlaucomaLens become opaqueHygiene(iii)ConjunctivitisCornea become dry and opaqueLaser Surgery(iv)XerophthalmiaIncreased pressure in the eyesLens replacement Surgery
Certain hormones released from the anterior lobe of pituitary gland are given.• Thyroid Stimulating Hormone (TSH)• Adreno Cortico Tropic Hormone (ACTH)• Gonadotropic Hormone (GTH)(a) Write the common feature of these hormones.(b) Write one function of ACTH and TSH.(c) Name two hormones secreted by the action of GTH.
Explain the following every day life experiences scientifically. (a) Spirit kept in an open watch glass is converted into the gaseous state even at room temperature. (b) The variation in atmosphere temperature do not effect our body temperature instantaneously. (c) Complete melting of ice-cream will not happen suddenly.
Solar energy is treated as the energy source of the future. Write any two solar devices working on solar energy that can be utilised in daily life.
Who is known as the father of Political Science?
(a) Select the statements related to the disease Haemophilia from the following :• Structure of haemoglobin changes.• The synthesis of proteins that help in the clotting of blood fails.• Oxygen Carrying Capacity of haemoglobin decreases.• Excess bleeding even through minor wounds.(b) Name the disease to which other statements are related.
In the figure OABC is a rectangle and its breadth is 3. Write the Co-ordinates of the vertices B and C.

The algebraic form for the sum of first n terms of an arithmetic sequence is 2n2 + 8n. How many consecutive terms of the sequence from the first, are to be added to get 330 ?

Discussion

No Comment Found

Related InterviewSolutions

Reply to Comment