Question 696339: find positive square root of equation 4x^2+ 7x = 15 complete square
Solving a Quadratic Equation by Completing the Square Found 3 solutions by stanbon, josmiceli, Alan3354:Answer by stanbon(75887) (Show Source):
You can put this solution on YOUR website! 4x^2+ 7x = 15 complete square
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4(x^2 + (7/4)x + ?) = 15 + 4*?
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4(x^2 + (7/4)x + (7/8)^2) = 15 + 4(7/8)^2
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4(x+(7/8))^2 = (15*64+28)/64
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4(x+(7/8)^2) = 988/64
(x+(7/8))^2 = 247/64
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x+(7/8) = sqrt(247)/8 or x+(7/8) = -sqrt(247/8
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x = [-7 + sqrt(247)]/8 or x = [-7-sqrt(247]/8
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Cheers,
Stan H.
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You can put this solution on YOUR website!
This is now in the right form to complete the square
Take 1/2 of the co-efficient of the term,
square it, then add it to both sides.
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Take the square root of both sides
And also take the negative square root of
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The roots are and
The factoring is
check:
Multiply both sides by
OK
Here's the plot
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