Question

How do you solve `2x ^ { 2} - 18= 0`?

Answer 1

`x=+-3`

Explanation:

`"add 18 to both sides"`

`2x^2cancel(-18)cancel(+18)=0+18`

`rArr2x^2=18`

`"divide both sides by 2"`

`rArrx^2=9`

`color(blue)"take the square root of both sides"`

`sqrt(x^2)=+-sqrt9larrcolor(blue)"note plus or minus"`

`rArrx=+-3`

Answer 2

Add 18, divide by 2, square root answer

Explanation:

Add 18, as you want to set `2x^2` equal to a number

`2x^2 = 18`

Divide it by 2, leaving only `x^2`

`x^2 = 9`

Square root the number

`x = sqrt(9)`
`x = 3` or `x = -3`