B = c(a-b) - b(a-c) = ac - bc -ba + bc = ac -ba = -ba + ac = -a(b - c ) = - (-50).2=100
=.= hk tốt!!
Ta có: B = c(a - b) - b(a - c)
B = ac - bc - ab + bc
B = ac - ab = -ab + ac = -a(b - c)
Thay a = -50; b - c = 2 vào biểu thức B, ta có:
-(-50).2 = 50.2 = 100
Vậy ...
\(B=c\left(a-b\right)-b\left(a-c\right)\)
\(B=ac-bc-ba+bc\)
\(B=ac-ba=a\left(c-b\right)=-a\left(b-c\right)\)
Thay a = -50 ; b - c = 2
\(\Rightarrow B=-\left(-50\right).2=100\)