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mrs_skeptik [129]
3 years ago
13

If x+y=5,then what is the value of x3+y3+15xy​

Mathematics
1 answer:
a_sh-v [17]3 years ago
5 0

Answer:

125

Step-by-step explanation:

x + y = 5

We need to have x^3 and y^3 in the expression, so cube both sides.

(x + y)^3 = 5^3

Expand the left side.

(x + y)(x + y)^2 = 125

(x + y)(x^2 + 2xy + y^2) = 125

x^3 + 2x^2y + xy^2 + x^2y + 2xy^2 + y^3 = 125

x^3 + 3x^2y + 3xy^2 + y^3 = 125

Now we need to separate x^3 + y^3.

x^3 + y^3 + 3x^2y + 3xy^2 = 125

We need to turn 3x^2y + 3xy^2 into 15xy.

Factor the GCF, 3xy, out of 3x^2y + 3xy^2.

x^3 + y^3 + 3xy(x + y) = 125

We know that x + y = 5, so substitute x + y with 5.

x^3 + y^3 + 3xy(5) = 125

x^3 + y^3 + 15xy = 125

Answer: 125

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Answer:

{1, 2, 3},  {3, 4, 5}

Step-by-step explanation:

Write expressions for three consecutive integers:  n, n + 1, n + 2.

Set up an equation for the verbal description: the product (mulitplication) of the two larger integers (the last two) is one less than 7 times the smallest (the first one).

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Multiply (FOIL) the left side.

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n^2 - 4n + 3 = 0

Factor.

(n - 1)(n - 3) = 0

Set the two factors equal to 0

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One set of integers begins with 1, so it's {1, 2, 3}.

The other set begins with 3, so it's {3, 4, 5}

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Answer:

Step-by-step explanation:

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Answer:

77

Step-by-step explanation:

Firstly, we need to calculate the total score of the junior students and the total score of the senior students.

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