Question

What are the possible values of x in 8x2 + 4x = -1?

Answer 1

The possible values of x are:

x=
`(-1+√(3))/(4) \,\,or\,\, x= 0.18`

and

x=
`(-1-√(3))/(4) \,\, or \,\, x= -0.68`

Explanation:

`8x^2+4x+1=0`

Using Quadratic formula to solve this equation:

`x=(-b\pm√(b^2-4ac))/(2a)\\a = 8 \,\, b = 4\,\, c = -1\\Putting \,\, values \,\, in \,\, the\,\, equation\\x= (-4\pm√((4)^2-4(8)(-1)))/(2(8))\\x= (-4\pm√(16+32))/(16)\\x= (-4\pm√(48))/(16)\\x= (-4+ √(48))/(16) \,\, and \,\, x= (-4- √(48))/(16)\\x= (-1+ √(3))/(4) \,\, and \,\, x= (-1- √(3))/(4)`

The possible values of x are:

x=
`(-1+√(3))/(4) \,\,or\,\, x= 0.18`

and

x=
`(-1-√(3))/(4) \,\, or \,\, x= -0.68`