Đáp án+Giải thích các bước giải:
1, x² - 2x + 1 - y²
= (x - 1)² - y²
=(x - 1 - y ).(x - 1 + y)
2, x² - 2xy + y² - 9z²
= (x - y)² - 9z²
= (x - y - 3z).(x - y + 3z)
3, x² - 4xy + 4y² - z² + 4zt - 4t²
= (x² - 4xy + 4y²) - (z² - 4zt + 4t²)
=( x - 2y)² - (z - 2t)²
= (x - 2y - z + 2t).(x - 2y + z - 2t)
4, $a^{4}$ - ax³ - ay + xy
= a(a³ - x³) - (ay - xy)
= a.(a- x).(a² + ax +x²) - y(a - x)
= (a - x).(a³ + a²x + ax² - y)
5, x² + 2x + 1 - y²
= (x + 1)² - y²
= (x + 1 - y).(x + 1 + y)
6, x² + 2xy + y² - 4z²
=(x + y )² - 4z²
= (x + y - 2z).(x + y + 2z)
7, x² - 2xy + y² - z² + 2zt - t²
= (x² - 2xy + y²) - (z² - 2zt + t²)
= (x - y)² - (z - t)²
= (x - y + z - t).(x - y - z + t)
8, a³ - ax² - ay + xy
= (a³ - ax² ) - (ay - xy)
= a(a² - x²) - y(a - x)
= a(a - x).(a + x) - y(a - x)
=(a - x).(a² + ax - y)
