We can be a bit clever and factor x 2 − 3 x − 4 = ( x − 4 ) ( x + 1 ) {\displaystyle x^{2}-3x-4=(x-4)(x+1)} then factor x − 4 {\displaystyle x-4} as a difference of squares where we think of x {\displaystyle x} as the square of x {\displaystyle {\sqrt {x}}} .
Hence
Combining gives