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Question
Solve the equation 3x² – x – 7 = 0 and give your answer correct to two decimal places.
Solution
3x² – x – 7 = 0
a = 3, b = -1, c = -7
x = `(-b ± sqrt(b^2 - 4ac))/(2a)`
= `-((-1) ± sqrt((-1)^2 - 4.3. (-7)))/(2 xx 3)`
= `(1 ± sqrt(1 + 84))/(6)`
= `( 1 ± sqrt(85))/(6)`
= `(1 ± 9·216)/(6)`
x = `( 1 + 9.216)/(6) and (1 - 9.216)/(6)`
= `(10.216)/(6) and -(8.216)/(6)`
= 1·703 and -1·37.
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