Question

Dacă
$a + b = 2 \sqrt{3}$
si
$b - c = \frac{ \sqrt{3} }{2}$

,calculați ab+b^2-ac-bc.

Answer 1

a+b=2√3
b-c=√3 /2

ab+b^2-ac-bc=b(a+b)-c(a+b)=(a+b)(b-c)=2√3 ·√3 /2=3