Question Details

It is given that x and y are integers in the following equation: (x +y−7)2 +(y+3x−13)2 = 0


The value of (x3 +y3) is ________(in integer).

Options

A

91

B

85

C

87

D

95

Show Answer

Correct Answer :

Option A

91

Solution :

The correct option is 91.

Step 1: Understand the behavior of squared terms
We are given the following equation where x and y are integers:
( x + y - 7 ) 2 + ( y + 3 x - 13 ) 2 = 0
For any real numbers A and B, their squares are non-negative:
A 2 0 and B 2 0
For the sum of two non-negative terms to equal zero, both individual terms must be exactly zero:
A 2 + B 2 = 0 A = 0 and B = 0

Step 2: Set up the system of linear equations
Applying this property to our equation, we obtain two simultaneous equations:
x + y - 7 = 0 x + y = 7 (Equation 1)
and
y + 3 x - 13 = 0 3 x + y = 13 (Equation 2)

Step 3: Solve the system of equations
We can solve for x by subtracting Equation 1 from Equation 2:
( 3 x + y ) - ( x + y ) = 13 - 7
Simplifying the terms:
2 x = 6
x = 3
Now, substitute x = 3 back into Equation 1 to find y:
3 + y = 7
y = 4
Since both x = 3 and y = 4 are integers, they satisfy the conditions of the problem.

Step 4: Compute the final value
We need to find the value of:
x 3 + y 3
Substitute x = 3 and y = 4:
3 3 + 4 3 = 27 + 64 = 91

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