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Question
Solve for x the quadratic equation x2 - 4x - 8 = 0.
Give your answer correct to three significant figures.
Solution
`x^2 - 4x - 8 = 0`
Comparing the above equation by `ax^2 +bx + c = 0`
a = 1 , b = -4 , c = - 8
`x = (-2 +- sqrt(b^2 -4 ac))/(2a)`
`x = (4+- sqrt(-4)^2 - 4 xx 1 xx (-8))/(2xx1)`
`x =(4+- sqrt(16+32))/2`
`x = (4+- sqrt(48))/2`
`x = (4+- 6.928)/2`
x = 5.46 and -1.46 {approx}
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