If a and b are two positive real numbers such that a + b = 20 and ab =

1.	If a and b are two positive real numbers such that a + b = 20 and ab = 4, then the value of a3 + b3 is:1. 77602. 2403. 80004. 8240
Answer» Correct Answer - Option 1 : 7760 Given: a and b are two positive real numbers such that a + b = 20 and ab = 4. We have to find the value of a³ + b³ Formula Used: a3 + b³ = (a + b)³ – 3ab(a + b) Calculation: a3 + b3 = (a + b)3 – 3ab(a + b) ⇒ a3 + b³ = (20)³ – 3 × 4 × 20 [∵ Given a + b = 20 and ab = 4] ⇒ a3 + b³ = 20 × (20² – 12) ⇒ a3 + b³ = 20 × (400 – 12) ⇒ a3 + b³ = 20 × 388 ⇒ a3 + b³ = 7760 ∴ Value of a3 + b³ is 7760

If a and b are two positive real numbers such that a + b = 20 and ab = 4, then the value of a3 + b3 is:1. 77602. 2403. 80004. 8240

Answer» Correct Answer - Option 1 : 7760

Given:

a and b are two positive real numbers such that a + b = 20 and ab = 4. We have to find the value of a³ + b³

Formula Used:

a3 + b³ = (a + b)³ – 3ab(a + b)

Calculation:

a3 + b3 = (a + b)3 – 3ab(a + b)

⇒ a3 + b³ = (20)³ – 3 × 4 × 20 [∵ Given a + b = 20 and ab = 4]

⇒ a3 + b³ = 20 × (20² – 12)

⇒ a3 + b³ = 20 × (400 – 12)

⇒ a3 + b³ = 20 × 388

⇒ a3 + b³ = 7760

∴ Value of a3 + b³ is 7760

Discussion

No Comment Found

Related InterviewSolutions

If the remainder when 2x3 + 3x2 – 5kx + 15 is divided by x – k is 2k3, then find the value of k.1. ±√(15/2)2. ±√(5/2)3. ±√154. ±√2
Find the value of k for which the roots are real and equal in the following equation:Kx2 – 2√5x + 4 = 0 1. 5/42. √53. 2√34. 4/5
If x2 - 5x + 1 = 0, then the value of \(\left(x^4 + \frac 1 {x^2}\right) \div \left(x^2 + 1\right)\) is:1. 252. 213. 224. 24
यदि `x=3+2sqrt(2)` और `xy=1` है तो `(x^(2)+3xy+y^(2))/(x^(2)-3xy+y^(2))` का मान ज्ञात करें।A. `30/31`B. `70/31`C. `35/31`D. `37/31`
Salary of 2 teachers and 4 peons is 28000 rupees, whereas salary of 2 teacher and 7 peon is 34000 rupees, then find out the salary of a teacher.1. 80002. 90003. 100004. 11000
If a2x + b2y + c2z = 9x + 121y + 81z, where a, b, c are positive integers, then find the value of c + a - b1. 12. -313. -14. 5
If x + y = 5 and xy = 6, find the value of x - y. Given that x > y1. 12. 213. -14. 13
A spends Rs. 56,000 to purchase a certain number of laptops. The price of one laptop is Rs. 2,000. If the price of a laptop rises by 75%. Then find how many laptops should be purchased less so that the expenditure should remain constant.1. 102. 123. 254. 15
A kurta cost Rs. 12 more than the cost of a shirt. The total cost of 2 such Kurtas and 5 such shirts is Rs. 234. The cost of 3 shirts is: 1. Rs. 902. Rs. 423. Rs. 304. Rs. 60
In the given question, two equations numbered I and II are given. Solve both the equations and mark the appropriate answer.I. x2 - 7x + 12 = 0II. y2 - 5y + 6 = 01. x > y2. x < y3. x ≥ y4. x ≤ y5. x = y or the relationship between x and y can not be established.

If a and b are two positive real numbers such that a + b = 20 and ab = 4, then the value of a3 + b3 is:1. 77602. 2403. 80004. 8240

Discussion

No Comment Found

Related InterviewSolutions

Reply to Comment