Question 690122
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1 - a²-2ab-b^2

Factor -1 out of the last three terms:

1 - (a²+2ab+b²)

Factor the parentheses:

1 - (a+b)(a+b)

1 - (a+b)²

1² - (a+b)²

That's the difference of squares:

[1 - (a+b)][1 + (z+b)]

[1 - a - b][1 + a + b]

(1 - a - b)(1 + a + b)

Edwin</pre>