Question

If x+y= -7 and xy=10, then x³+y³ is

Answer 1

Step-by-step explanation:

x +y = -7

(x+y)³= -7³. [cubing both side ]

x³ + y³ + 3xy(x+y) = -343

x³ + y³ +3 × 10 × -7= -343

x³ + y³ = -343 + 210

x³ + y³ = - 133

tell me if it is the right answer

Answer 2

Given :

• x+y= -7

• xy=10

To find :

• x³+y³

Formula used :

• ( a+b)³ = a³+ b³ + 3 ab ( a+b )

Solution :

⟹ ( x+y)³ = x³+ y³ + 3 xy ( x+y )

It is given that , x+y= -7 and xy=10

⟹ ( -7 )³ = x³+ y³ + [3 × 10 (-7 )]

⟹ -343 = x³+ y³ + (-210)

⟹ -343 + 210 = x³+ y³

⟹ -133 = x³+ y³

Answer : -133

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Learn more:-

$\implies{(a+b)^2 = a^2 + b^2 + 2ab}$

$\implies{(a-b)^2 = a^2 + b^2 - 2ab}$

$\implies{(a+b)^3 = a^3 + b^3 + 3ab(a + b)}$

$\implies{(a-b)^3 = a^3 - b^3 - 3ab(a-b)}$

$\implies{(a^3+b^3)= (a+b)(a^2 - ab + b^2)}$

$\implies{(a^3-b^3)= (a-b)(a^2 + ab + b^2)}$

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