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146) If the sum of 2 numbers is 1 and their product is 1, then what is the sum of their cubes?

User Lqbweb
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Given that the sum of 2 numbers is 1 and their product is 1, let's find the sum of their cubes.

Let x and y represent the numbers.

Thus, we have:

x + y = 1..........................equation 1

x y = 1...........................equation 2

Here, we are to find x³ + y³ .

Thus, we can write this as:


x^3+y^3=(x+y)(x^2+y^2-xy)

Manipulating this, we can write:


x^3+y^3=(x+y)((x+y)^2-3xy))

Substitute the values for x+y and xy into the equation above, we have:


\begin{gathered} x^3+y^3=(1)((1)^2-3(1)) \\ \\ x^3+y^3=(1)(1-3) \\ \\ x^3+y^3=-2 \end{gathered}

Therefore, the sum of their cubes is -2.

ANSWER:

-2

User Oberblastmeister
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