Respuesta :

Answer:

2

Step-by-step explanation:

devishri1977

Answer:

Step-by-step explanation:

437 = (21 + x)(21 - x)

(21 + x)(21 - x) = 437             {(a + b)(a - b)= a² - b²}

21² - x² = 437

441 - x² = 437          {subtract 441 from both sides}

-x² = 437 - 441  

-x² = - 4             {Divide both sides by [-1] }

x² = 4

x² = 2²

x = 2