Question

Which equation shows the quadratic formula used correctly to solve 7x2 = 9 + x for x?

Answer 1

`(1 +/- √(253) )/(14)`

You can get this by using the quadratic equation with a = 7, b = -1, c = -9

Answer 2

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

`7x^(2)=9+x`

Equate the equation to zero

`7x^(2)-x-9=0`

so

`a=7\\b=-1\\c=-9`

substitute in the formula

`x=\frac{-(-1)(+/-)\sqrt{(-1)^(2)-4(7)(-9)}} {2(7)}`

`x=\frac{1(+/-)√(1+252)} {14}`

`x=(1(+/-)√(253))/(14)`

therefore

the answer is

`x=(1(+/-)√(253))/(14)`