Question

solue 7x²+2x - 1 = 0 by
completely square​

Answer 1

Given:-

7x²+2x - 1 = 0

Formula:-

$- b + - \frac{ \sqrt{ {b}^{2} - 4ac } }{2a}$

Solution:-

a=7

b=2

c= -1

Applying formula:-

$- 2 + - \frac{ \sqrt{ {( - 2)}^{2} - 4 \times 7 \times - 1 } }{2 \times 7}$

$= - 2 + - \frac{ \sqrt{4 + 28} }{14}$

$= - 2 + - \frac{ \sqrt{32} }{14}$

$= - 2 + - \frac{ \sqrt{ {2}^{5} } }{14}$

$= - 2 + - \frac{4 \sqrt{2} }{14}$

$= - 2 + - \frac{4 \times 1.414}{14}$

$= - 2 + - \frac{5.656}{14}$

= -2+-0.404

Root 1:-

= -2+0.404

= -1.596

Root 2:-

= -2-0.414

= -2.414