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Minimize Q=3x2+3y2​, where x+y=6.

User DarrylG
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2 Answers

11 votes

Answer:


+(x + y) {}^(2) = 6 {}^(2) \\ x {}^(2) + 2xy + y {?}^(2) = 36


x {}^(2) + y {}^(2) = 36 - 2xy


q = 3(x {}^(2) + y {}^(2) )


q = 3(36 - 2xy) = 108 - 6xy

User Varun Malhotra
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3.6k points
11 votes

To minimize Q=3x^2+3y^2, we need to solve the system of equations x+y=6 and Q=3x^2+3y^2. Taking the derivative of Q and setting it equal to zero, we find x=3. Substituting x=3 into x+y=6 gives us y=3. Therefore, the minimum value of Q is obtained when x=3 and y=3.

To minimize Q=3x2+3y2, we need to find the values of x and y that satisfy the condition x+y=6. This can be done by solving the system of equations:

x+y=6

Substituting y=6-x into Q=3x2+3y2, we get:

Q=3x2+3(6-x)2

Simplifying and expanding, we have:

Q=3x2+3(36-12x+x2)

Q=3x2+108-36x+3x2

Combining like terms, we get:

Q=6x2-36x+108

To minimize Q, we can take the derivative of Q with respect to x and set it equal to zero:

dQ/dx=12x-36=0

Solving for x, we find x=3.

Substituting x=3 into the equation x+y=6, we get y=3.

Therefore, the minimum value of Q is obtained when x=3 and y=3.

User Ruben Bartelink
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3.6k points