Question

solve and find the value of x3+y3+9xy if x+y=3

Answer 1

X+y=3
X=3-y
Substute this value in the main formula
(3-y)^3 + y3 + 9*(3-y)*y
${3}^{3} - 3 \times {3}^{2} \times y + 3 \times 3 \times {y}^{2} - {y}^{3} + {y}^{3} + 9 \times (3 - y) \times y$
27-27y+9y^2-y^3+y^3+27y-9y^2
All will be canceled except 27
Ans =27


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Answer 2

Answer:

Answer is 27

Step-by-step explanation:

Taking cube on both sides of x + y = 3 gives x3 + y3 + 3xy(x + y) = 27      ----(1)

And we know that x + y = 3

⇒ x3 + y3 + 3xy(x + y) = x3 + y3 + 3xy(3) = x3 + y3 + 9xy = 27 (From eq. 1)

∴ Value of x3 + y3 + 9xy = 27