If x + y = 3 then what is the value...

Home / Arithmetic Ability / Algebra / Question

Examveda

If x + y = 3, then what is the value of x³ + y³ + 9xy?

A. 15

B. 81

C. 27

D. 9

Answer: Option C

Solution (By Examveda Team)

x + y = 3
Put x = 1, y = 2
x³ + y³ + 9xy
= (1)³ + (2)³ + 9 × 2 × 1
= 1 + 8 + 18
= 27

Alternate:
x + y = 3 . . . . . . (1)
On taking cube on both sides
(x + y)³ = (3)³
x³ + y³ + 3xy(x + y) = 27
x³ + y³ + 3xy(3) = 27
x³ + y³ + 9xy = 27

This Question Belongs to Arithmetic Ability >> Algebra

Join The Discussion

Related Questions on Algebra

If a * b = 2a - 3b + ab, then 3 * 5 + 5 * 3 is equal to?

A. 22

B. 24

C. 26

D. 28

View Answer

If $$p \times q = p + q + \frac{p}{q}{\text{,}}$$ then the value of 8 × 2 is?

A. 6

B. 10

C. 14

D. 16

View Answer

The value of $$\left( {{\text{1 + }}\frac{1}{x}} \right)$$ $$\left( {{\text{1 + }}\frac{1}{{x + 1}}} \right)$$ $$\left( {{\text{1 + }}\frac{1}{{x + 2}}} \right)$$ $$\left( {{\text{1 + }}\frac{1}{{x + 3}}} \right)$$ is?

A. $$1 + \frac{1}{{x + 4}}$$

B. x + 4

C. $$\frac{1}{x}$$

D. $$\frac{{x + 4}}{x}$$

View Answer

If $$\frac{a}{b}{\text{ = }}\frac{2}{3}$$ and $$\frac{b}{c}{\text{ = }}\frac{4}{5}{\text{,}}$$ then the ration $$\frac{{a + b}}{{b + c}}$$ equal to?

A. $$\frac{{20}}{{27}}$$

B. $$\frac{{27}}{{20}}$$

C. $$\frac{6}{8}$$

D. $$\frac{8}{6}$$

View Answer