The positive root of t in the following equation, 4t2 + 7t – 1 = 0, correct to 4 places of decimal, is

A.
1.0622 
B.
10.6225 
C.
0.1328 
D.
0.3218 
E.
2.0132
Correct Answer: Option C
Explanation
(4t^{2} + 7t – 1 = 0)
Using a = 4, b = 7, c = 1.
(x = frac{b pm sqrt{b^{2} – 4ac}}{2a})
= (frac{7 pm sqrt{7^{2} – 4(4)(1)}}{2(4)})
= (frac{7 pm sqrt{49 + 16}}{8})
= (frac{7 pm sqrt{65}}{8})
= (frac{7 pm 8.0623}{8})
The positive answer = (frac{7 + 8.0623}{8} = frac{1.0623}{8})
(approxeq 0.1328) (4 decimal place)