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

Solution:

It is given that

x is a whole number

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

Using the algebraic identity a² - b² = (a + b) (a - b)

437 = 21² - x²

By further calculation

437 = 441 - x²

So we get

x² = 441 - 437

x² = 4

Taking the square root on the other side

x = ± 2

Therefore, the value of x is 2 and -2.

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

Summary:

 If x is a whole number and 437 = (21 + x) (21 - x), then x = 2 and -2.