Đáp án:
Giải thích các bước giải:
a, ax + bx + ay + by
= x ( a+b ) + y ( a+b )
= ( z + b ) ( x + y )
b, x²y + xy² - x - y
= xy ( x + y ) - ( x + y )
= ( x+y ) ( xy -1 )
c, x² + xy - 5x - 5y
= x ( x + y) -5 ( x + y )
= ( x + y) ( x- 5)
d, ax + ay - 7x - 7y e, $x^{4 }$ + x³ + x + 1
= a ( x + y ) - 7( x + y ) = x³ ( x + 1 ) + ( x + 1 )
= ( x + y) ( a - 7) = ( x³ + 1 )( x + 1 )
f, 5x² + 3( x + y ) - 5y²
= ( 5x² - 5y² ) + 3( x + y )
= 5 ( x² - y² ) + 3( x+y)
= 5 ( x - y )(x + y ) + 3( x + y )
= ( x + y ) [ 5(x-y) + 3 ]
= ( x + y) ( 5x - 5y + 3)
