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How can I factor 5x^2 + 26x - 24 = 0 using the completing the square method.

User Druubacca
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2 Answers

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15 votes
The answer is -8 with using the completing the square method
User Perryn Fowler
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16 votes
16 votes

QUADRATIC EQUATION


\mathbb{ANSWER:}


  • \bold{x = 0.8 \: } \: \sf \: {\color{grey}or} \: \: \: \bold{ x= (4)/(5) } \\


  • \bold{x = - 6}

— — — — — — — — — —

Explanation:

How can we factor 5x^2 + 26x - 24 = 0 using the completing the square method?

Let's solve your equation step-by-step.


\bold{Given \: Equation: \color{brown} 5x²+26x-24=0}

First, add 24 to both sides.


  • \bold{5x²+26x-24 - \purple{ 24} = 0 + \purple{24}}


  • \bold{ \implies \: 5x²+26x = 24 }

Since the coefficient of 5x² is 5, divide both sides by 5.


  • \bold{ \frac{5 {x}^(2) + 26x }{5} = (24)/(5) } \\


  • \bold{ \implies \: {x}^(2) + (26)/(5) x = (24)/(5) } \\

The coefficient of 26/5x is 26/5. So, let b=26/5.

Then we need to add (b/2)²=169/25 to both sides to complete the square.

Add 169/25 to both sides.


  • \bold{ {x}^(2) + (26)/(5) x + \frac{ \purple{169}}{ \purple{25}}= (24)/(5) + \frac{ \purple{169}}{ \purple{25}} } \\


  • \bold{ \implies \:\bold{ {x}^(2) + (26)/(5) x + \frac{ 169}{ {25}}= (289)/(25) } } \\

Factor the left side.


  • \bold{(x + (13)/(5) ) {}^(2) = (289)/(25) } \\

Take square root.


  • \bold{x + (13)/(5) = ± \: \sqrt{ (289)/(25) }} \\

Then, add (-13)/5 to both sides.


  • \bold{x + (13)/(5) + \frac{\purple{ - 13} }{\purple{ 5}} = \frac{{ - 13} }{{ 5}} ± \: \sqrt{ (289)/(25)}} \\


  • \bold{ \: x = ( - 13)/(5) ± \sqrt{ (289)/(25) } } \\


  • \implies \: \underline{ \boxed{ \bold{ (4)/(5) } \sf \: \: or \: \: \bold{ x = - 6}}} \\

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User Barrie Reader
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