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How to solve the equation by factoring 5x^2=45?

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mycreeam | Student, Undergraduate | (Level 1) eNoter

Posted July 28, 2011 at 12:57 AM via web

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How to solve the equation by factoring 5x^2=45?

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giorgiana1976 | College Teacher | (Level 3) Valedictorian

Posted July 28, 2011 at 1:00 AM (Answer #1)

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First, we'll have to move all terms to one side:

5x^2 - 45 = 0

We'll factorize by 5 to the left:

5(x^2 - 9) = 0

We'll divide by 5 both sides:

x^2 - 9 = 0

We'll re-write the difference of the squares as a product:

(x-3)(x+3) = 0

We'll cancel each factor:

x + 3 = 0

x = -3

x - 3 = 0

x =3

The solutions of the equation are {-3 ; 3}.

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sanduniiii | Student, Grade 10 | (Level 1) Honors

Posted July 28, 2011 at 1:04 AM (Answer #2)

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5X^2 - 45 = 0

5( x^2 - 9) = 0

therefore:-  (x^2 - 9 ) =0

x^2 = 9

x=squareroot of 3

x = 3

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tonys538 | TA , Undergraduate | (Level 1) Valedictorian

Posted December 31, 2014 at 4:43 PM (Answer #3)

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The equation 5x^2=45 has to be solved.

5x^2=45

Divide both sides of the equation by 5 to cancel the common  factor

(5x^2)/5 = 45/5

x^2 = 9

Subtract 9 from both the sides

x^2 - 9 = 0

x^2 - 3^2 = 0

Use the expansion x^2 - y^2 = (x - y)(x + y)

This gives:

(x - 3)(x + 3) = 0

x - 3 = 0 gives x = 3

x + 3 = 0 gives x = -3

The solution of the equation is x = 3 and x = -3

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