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Solve for all values of x

Solve for all values of x-example-1
User Anigel
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\cfrac{x+3}{x-8}~~ + ~~\cfrac{7}{x-6}~~ = ~~\cfrac{7}{x-6}\implies \cfrac{x+3}{x-8}~~ = ~~\stackrel{\textit{\LARGE like-terms}}{\cfrac{7}{x-6}~~ - ~~\cfrac{7}{x-6}} \\\\\\ \cfrac{x+3}{x-8}=0\implies x+3=0\implies x=-3

User Aemyl
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x + 3/x - 8 + 7/x-6=7/x-6

Variable x cannot be equal to any of the values 6.8 as division by zero is not defined. Multiply both sides of the equation by (x−8)(x−6), the lowest common denominator of x−8,x−6.

(x - 6)(x + 3) + (x - 8) × 7 = (x - 8) × 7

Use the distributive property to multiply x−6 by x+3 and combine like terms.

x² - 3x - 18 + ( x- 8) × 7 = (x - 8) × 7

Use the distributive property to multiply x−8 by 7.

x² - 3x - 18 + 7x - 56 = (x - 8) × 7

Combine −3x and 7x to get 4x.

x²+ 4x - 18 - 56 = (x - 8) × 7

Subtract 56 from −18 to get −74.

x² +4x - 74 = (x - 8) × 7

Use the distributive property to multiply x−8 by 7.

x² + 4x - 74 = 7x - 56

Subtract 7x on both sides.

x² + 4x - 74 - 7x = -56

Combine 4x and −7x to get −3x.

x² - 3x - 74= -56

Add 74 to both sides.

x² - 3x = - 56 + 74

Add −56 and 74 to get 18.

x² - 3x = 18

Divide −3, the coefficient of the x term, by 2 to get -3/2. Next, add the square of -3/2. to both sides of the equation. This step makes the left side of the equation a perfect square.

x² + 3x + (-3/2)² = 18 + (-3/2)²

Gets the square of − 3/2. To do this, find the square of the numerator and the denominator of the fraction.

x² + 3x + 9/4 = 18 + 9/4

Add 18 and 4/9.

x² + 3x + 9/4 + 81/4

Factor to x² + 3x + 9/4. In general, when x² + bx + c is a perfect square, it can always be factored as (x + b/2)².

( x - 3/2)² = 81/4

Take the square root of both sides of the equation.


\boldsymbol{\sf{\sqrt{\left(x-(3)/(2)\right) }=\sqrt{(81)/(4) } }}

Simplify.

x - 3/2 = 9/2

x - 3/2 = - 9/2

Add 3/2 to both sides of the equation.

x = 6

x = -3

The variable x cannot be equal to 6.

x = -3

User Tumtumtum
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