If x is a whole number and 437 = (21 + x)(21 - x), then x =

Hey there :)

We know that ( a + b )( a - b ) is a² - b²

So here we apply this formula
( 21 + x )( 21 - x ) = 21² - x²

437 = 21² - x²
437 = 441 - x²
Rearrange the equation
x² = 441 - 437
x² = 4


x = +2 or -2

Answers4.) -1/205.) -1/406.) -55/127.) -3/4