Question

HELP PLZZ!!

What are the solutions of the quadratic equation below?


2x2 - 2x - 9 = 0



`A. (-1± √(19) )/(2) \\B. (3± √(19) )/(2) \\\\C. (1± √(19) )/(2) \\\\D. (-1±3 √(19) )/(2) \\`

Answer 1

Option C.
`x=\frac{1(+/-)√(19)} {2}`

Explanation:

we know that

The formula to solve a quadratic equation of the form
`ax^(2) +bx+c=0` is equal to

`x=\frac{-b(+/-)\sqrt{b^(2)-4ac}} {2a}`

in this problem we have

`2x^(2) -2x-9=0`

so

`a=2\\b=-2\\c=-9`

substitute in the formula

`x=\frac{2(+/-)\sqrt{-2^(2)-4(2)(-9)}} {2(2)}`

`x=\frac{2(+/-)√(76)} {4}`

`x=\frac{2(+/-)2√(19)} {4}`

`x=\frac{1(+/-)√(19)} {2}`