What is the x value in x2-4 equals 0?

Answer 1

x^2 - 4 = 0

What you have to recognise is that the constant '4' is a 'squared number.

4 = 2^2

So we can write

x^2 - 2^2 = 0

Next remember that two squared terms with negative between then, factors.

Hence

x^2 - 2^2 = 0

=>

( x - 2)(x + 2) = 0

NB Note the plus (+) sign in the second bracket.

Hence

x - 2 = 0

x = 2

&

x + 2 = 0

x = -2

So 'x' can take two values, they are '(+)2, & -2'.

NB Note that two squared terms with a plus(+) between then , does NOT factor. e.g. the Pythagorean equation. c^2 = a^2 + b^2

Answer 2

If x2 - 4 = 0 then x2 = 4

⇒ x = 2 or x = -2.