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6. Find the equation of the tangent plane at the point (1,1) to the function f(x,y)=√x³+y³

User Jiluo
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Final answer:

The equation of the tangent plane at the point (1,1) to the function f(x,y)=√(x³+y³) is z = (3/2)x + (3/2)y - (√2 - 3).

Step-by-step explanation:

To find the equation of the tangent plane at the point (1,1) to the function f(x,y)=√(x³+y³), we first need to compute the partial derivatives of f with respect to x and y.

The partial derivative of f with respect to x, denoted as fx, is given by:

fx(x,y) = (1/2)(x³+y³)-1/2 · 3x²

Similarly, the partial derivative of f with respect to y, denoted as fy, is:

fy(x,y) = (1/2)(x³+y³)-1/2 · 3y²

We then evaluate these derivatives at the given point (1,1):

fx(1,1) = (3/2)

fy(1,1) = (3/2)

Now we have the gradient vector of f at the point (1,1), which is ⟨3/2, 3/2⟩. The tangent plane to f at (1,1) can be expressed as:

z - f(1,1) = fx(1,1)(x - 1) + fy(1,1)(y - 1)

Since f(1,1) = √(1³+1³) = √2, the equation becomes:

z - √2 = (3/2)(x - 1) + (3/2)(y - 1)

Rearranging the terms, we obtain the equation of the tangent plane:

z = (3/2)x + (3/2)y - (√2 - 3)

User ADJenks
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