Question

If (x2 - 1) = 4, what is the value of statement x2 - (x - 1)(x + 1) - 1​

Answer 1

Note:

a^2 - b^2 = ( a - b ) ( a + b )

Statement

x^2 - ( x - 1 ) ( x + 1 ) - 1

=> x^2 - [ ( x - 1 ) ( x + 1 ) ] - 1

=> x^2 - [ x^2 - 1^2 ] - 1

=> x^2 - ( x^2 - 1 ) - 1

=> x^2 - x^2 + 1 - 1

=> 0