Question

Expand (x—2y+6)(x—2y—6)

Answer 1

The answer is x^2 - 4xy+4y^2- 36. Trigonometric identity is being used.

Answer 2

$(x - 2y + 6)(x - 2y - 6)$

using

$(a + b)(a - b) = a {}^{2} - b {}^{2}$

$(x - 2y) {}^{2} - (6) {}^{2}$

$x {}^{2} + 4y {}^{2} - 4xy - 36$

$\large{vergilmustdie}$