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Find all the solutions to \[\frac{x+4}{x+5} = \frac{x-5}{2x}.\]
Find all the solutions to\[(x+4)/(x+5) = (x-5)/(2x).\]

User Ayushi Jha
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1 Answer

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Answer:

x = -4 + 3 i or x = -4 - 3 i

Explanation:

Solve for x:

(x + 4)/(x + 5) = (x - 5)/(2 x)

Hint: | Multiply both sides by a polynomial to clear fractions.

Cross multiply:

2 x (x + 4) = (x - 5) (x + 5)

Hint: | Write the quadratic polynomial on the left hand side in standard form.

Expand out terms of the left hand side:

2 x^2 + 8 x = (x - 5) (x + 5)

Hint: | Write the quadratic polynomial on the right hand side in standard form.

Expand out terms of the right hand side:

2 x^2 + 8 x = x^2 - 25

Hint: | Move everything to the left hand side.

Subtract x^2 - 25 from both sides:

x^2 + 8 x + 25 = 0

Hint: | Using the quadratic formula, solve for x.

x = (-8 ± sqrt(8^2 - 4×25))/2 = (-8 ± sqrt(64 - 100))/2 = (-8 ± sqrt(-36))/2:

x = (-8 + sqrt(-36))/2 or x = (-8 - sqrt(-36))/2

Hint: | Express sqrt(-36) in terms of i.

sqrt(-36) = sqrt(-1) sqrt(36) = i sqrt(36):

x = (-8 + i sqrt(36))/2 or x = (-8 - i sqrt(36))/2

Hint: | Simplify radicals.

sqrt(36) = sqrt(4×9) = sqrt(2^2×3^2) = 2×3 = 6:

x = (-8 + i×6)/2 or x = (-8 - i×6)/2

Hint: | Factor the greatest common divisor (gcd) of -8, 6 i and 2 from -8 + 6 i.

Factor 2 from -8 + 6 i giving -8 + 6 i:

x = 1/2-8 + 6 i or x = (-8 - 6 i)/2

Hint: | Cancel common terms in the numerator and denominator.

(-8 + 6 i)/2 = -4 + 3 i:

x = -4 + 3 i or x = (-8 - 6 i)/2

Hint: | Factor the greatest common divisor (gcd) of -8, -6 i and 2 from -8 - 6 i.

Factor 2 from -8 - 6 i giving -8 - 6 i:

x = -4 + 3 i or x = 1/2-8 - 6 i

Hint: | Cancel common terms in the numerator and denominator.

(-8 - 6 i)/2 = -4 - 3 i:

Answer: x = -4 + 3 i or x = -4 - 3 i

User Jstol
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