Solve 9x 8y = -7 - ScanMath

Question

Solve the equation

Solve for x

Solve for y

x = - \frac{7}{72 y}

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Testing for symmetry

Testing for symmetry about the origin

Testing for symmetry about the x-axis

Testing for symmetry about the y-axis

Symmetry with respect to the origin

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Rewrite the equation

r = \frac{7}{6 - sin ( 2 θ )} r = - \frac{7}{6 - sin ( 2 θ )}

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Find the first derivative

Find the derivative with respect to x

Find the derivative with respect to y

\frac{d y}{d x} = - \frac{y}{x}

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Find the second derivative

Find the second derivative with respect to x

Find the second derivative with respect to y

\frac{d ^{2} y}{d x ^{2}} = \frac{2 y}{x ^{2}}

Calculate

9 x 8 y = - 7

Simplify the expression

72 x y = - 7

Take the derivative of both sides

\frac{d}{d x} (72 x y) = \frac{d}{d x} (- 7)

Calculate the derivative

More Steps

72 y + 72 x \frac{d y}{d x} = \frac{d}{d x} (- 7)

Calculate the derivative

72 y + 72 x \frac{d y}{d x} = 0

Move the expression to the right-hand side and change its sign

72 x \frac{d y}{d x} = 0 - 72 y

Removing 0 doesn't change the value,so remove it from the expression

72 x \frac{d y}{d x} = - 72 y

Divide both sides

\frac{72 x \frac{d y}{d x}}{72 x} = \frac{- 72 y}{72 x}

Divide the numbers

\frac{d y}{d x} = \frac{- 72 y}{72 x}

Divide the numbers

More Steps

\frac{d y}{d x} = - \frac{y}{x}

Take the derivative of both sides

\frac{d}{d x} (\frac{d y}{d x}) = \frac{d}{d x} (- \frac{y}{x})

Calculate the derivative

\frac{d ^{2} y}{d x ^{2}} = \frac{d}{d x} (- \frac{y}{x})

Use differentiation rules

\frac{d ^{2} y}{d x ^{2}} = - \frac{\frac{d}{d x} ( y ) \times x - y \times \frac{d}{d x} ( x )}{x ^{2}}

Calculate the derivative

More Steps

\frac{d ^{2} y}{d x ^{2}} = - \frac{\frac{d y}{d x} \times x - y \times \frac{d}{d x} ( x )}{x ^{2}}

Use \frac{d}{d x} x^{n} = n x^{n - 1} to find derivative

\frac{d ^{2} y}{d x ^{2}} = - \frac{\frac{d y}{d x} \times x - y \times 1}{x ^{2}}

Use the commutative property to reorder the terms

\frac{d ^{2} y}{d x ^{2}} = - \frac{x \frac{d y}{d x} - y \times 1}{x ^{2}}

Any expression multiplied by 1 remains the same

\frac{d ^{2} y}{d x ^{2}} = - \frac{x \frac{d y}{d x} - y}{x ^{2}}

Use equation \frac{d y}{d x} = - \frac{y}{x} to substitute

\frac{d ^{2} y}{d x ^{2}} = - \frac{x ( - \frac{y}{x} ) - y}{x ^{2}}

Solution

More Steps

\frac{d ^{2} y}{d x ^{2}} = \frac{2 y}{x ^{2}}

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Conic

\frac{( y ^{'} ) ^{2}}{\frac{7}{36}} - \frac{( x ^{'} ) ^{2}}{\frac{7}{36}} = 1

Evaluate

9 x \times 8 y = - 7

Move the expression to the left side

9 x \times 8 y - (- 7) = 0

Calculate

More Steps

72 x y + 7 = 0

The coefficients A,B and C of the general equation are A= 0,B= 72 and C= 0

A = 0 B = 72 C = 0

To find the angle of rotation θ,substitute the values of A,B and C into the formula cot (2 θ) = \frac{A - C}{B}

cot (2 θ) = \frac{0 - 0}{72}

Calculate

cot (2 θ) = 0

Using the unit circle,find the smallest positive angle for which the cotangent is 0

2 θ = \frac{π}{2}

Calculate

θ = \frac{π}{4}

To rotate the axes,use the equation of rotation and substitute \frac{π}{4} for θ

x = x^{'} cos (\frac{π}{4}) - y^{'} sin (\frac{π}{4}) y = x^{'} sin (\frac{π}{4}) + y^{'} cos (\frac{π}{4})

Calculate

x = x^{'} \times \frac{2}{2} - y^{'} sin (\frac{π}{4}) y = x^{'} sin (\frac{π}{4}) + y^{'} cos (\frac{π}{4})

Calculate

x = x^{'} \times \frac{2}{2} - y^{'} \times \frac{2}{2} y = x^{'} sin (\frac{π}{4}) + y^{'} cos (\frac{π}{4})

Calculate

x = x^{'} \times \frac{2}{2} - y^{'} \times \frac{2}{2} y = x^{'} \times \frac{2}{2} + y^{'} cos (\frac{π}{4})

Calculate

x = x^{'} \times \frac{2}{2} - y^{'} \times \frac{2}{2} y = x^{'} \times \frac{2}{2} + y^{'} \times \frac{2}{2}

Substitute x and y into the original equation 72 x y + 7 = 0

72 (x^{'} \times \frac{2}{2} - y^{'} \times \frac{2}{2}) (x^{'} \times \frac{2}{2} + y^{'} \times \frac{2}{2}) + 7 = 0

Calculate

More Steps

36 (x^{'})^{2} - 36 (y^{'})^{2} + 7 = 0

Move the constant to the right-hand side and change its sign

36 (x^{'})^{2} - 36 (y^{'})^{2} = 0 - 7

Removing 0 doesn't change the value,so remove it from the expression

36 (x^{'})^{2} - 36 (y^{'})^{2} = - 7

Multiply both sides of the equation by - \frac{1}{7}

(36 (x^{'})^{2} - 36 (y^{'})^{2}) (- \frac{1}{7}) = - 7 (- \frac{1}{7})

Multiply the terms

More Steps

- \frac{36}{7} (x^{'})^{2} + \frac{36}{7} (y^{'})^{2} = - 7 (- \frac{1}{7})

Multiply the terms

More Steps

- \frac{36}{7} (x^{'})^{2} + \frac{36}{7} (y^{'})^{2} = 1

Use a = \frac{1}{\frac{1}{a}} to transform the expression

- \frac{( x ^{'} ) ^{2}}{\frac{7}{36}} + \frac{36}{7} (y^{'})^{2} = 1

Use a = \frac{1}{\frac{1}{a}} to transform the expression

- \frac{( x ^{'} ) ^{2}}{\frac{7}{36}} + \frac{( y ^{'} ) ^{2}}{\frac{7}{36}} = 1

Solution

\frac{( y ^{'} ) ^{2}}{\frac{7}{36}} - \frac{( x ^{'} ) ^{2}}{\frac{7}{36}} = 1

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