Question

find the zeroes of the polynomial f(x) =x square + 5x-4​

Answer 1

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By using quadratic formula

$\large\implies \boxed{\sf x = \dfrac{ - b\pm \sqrt{ {b}^{2} - 4ac} }{2a}}$

Here

• a = 1
• b = 5
• c = - 4

$\implies\sf x = \dfrac{ - 5\pm \sqrt{ {(5)}^{2} - 4 \times 1 \times ( - 4)} }{2 \times1 }$

$\implies\sf x = \dfrac{ - 5\pm \sqrt{ 25 + 16} }{2 }$

$\implies\sf x = \dfrac{ - 5\pm \sqrt{41} }{2 }$

Taking +ve sign

$\implies\sf x = \dfrac{ - 5 + \sqrt{41} }{2 }$

Taking -ve sign

$\implies\sf x = \dfrac{ - 5 - \sqrt{41} }{2 }$