How do you solve $3 x^{2} - 12 x = 9$ $3x^2 -12x = 9$ using the quadratic formula?

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How do you solve $3 x^{2} - 12 x = 9$ $3x^2 -12x = 9$ using the quadratic formula?

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Answer 1 · 2017-04-24T14:00:53

$x = 2 \pm \sqrt{7}$ $x=2+-sqrt7$

Explanation:

$rearrange terms and equate to zero$ $"rearrange terms and equate to zero"$

$\Rightarrow 3 x^{2} - 12 x - 9 = 0$ $rArr3x^2-12x-9=0$

$divide all terms by 3$ $"divide all terms by 3"$

$\Rightarrow x^{2} - 4 x - 3 = 0$ $rArrx^2-4x-3=0$

$compare to standard form a x^{2} + b x + c = 0$ $"compare to standard form " ax^2+bx+c=0$

$here a = 1, b = - 4 and c = - 3$ $"here " a=1,b=-4" and " c=-3$

$using the quadratic formula$ $"using the " color(blue)"quadratic formula"$

$color(red)(bar(ul(|color(white)(2/2)color(black)(x=(-b+-sqrt((b^2-4ac)))/(2a))color(white)(2/2)|)))$

$rArrx=(-(-4)+-sqrt((-4)^2-(4xx1xx-3)))/(2xx1)$

$color(white)(rArrx)=(4+-sqrt(16+12))/2=(4+-sqrt28)/2$

$color(white)(rArrx)=2+-1/2sqrt28$

$color(white)(rArrx)=2+-1/2sqrt(4xx7)$

$color(white)(rArrx)=2+-sqrt7$

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How do you solve $3 x^{2} - 12 x = 9$ $3x^2 -12x = 9$ using the quadratic formula?

1 Answer

Explanation:

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How do you solve $3 x^{2} - 12 x = 9$ $3x^2 -12x = 9$ using the quadratic formula?