Question

Bỏ dấu ngoặc:

a/ ( - a )( b - c + d )

b/ a( a + b ) - b( a + b ) - ( b - a )b

Answer 1

a) (-a)(b-c+d) = -ab + ac - ad

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

= a² + ab - ab - b² - b² + ab

= a ² +ab - b²