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Question
Solve the following equation for x and give, in the following case, your answer correct to 3 decimal places:
3x2 – 12x – 1 = 0
Solution
3x2 – 12x – 1 = 0
Here a = 3, b = –12 and c = –1
∴ `x = (-b +- sqrt(b^2 - 4ac))/(2a)`
`= (-(-12) +- sqrt((-12)^2 - 4(3)(-1)))/(2(3))`
`= (12 +- sqrt156)/6`
= `(12 +- 12.489)/6`
= `(12 + 12.489)/6` and `(12 - 12.489)/6`
= 4.082 and – 0.082
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