Question

Answer 1

\(A=3\sqrt{7}-\dfrac{5}{2}\cdot2\sqrt{7}-\dfrac{2}{3}\cdot3\sqrt{7}\\ A=3\sqrt{7}-5\sqrt{7}-2\sqrt{7}=-4\sqrt{7}\\ B=\sqrt{\left(\sqrt{5}-2\right)^2}-2\left(\sqrt{5}-1\right)\\ B=\sqrt{5}-2-2\sqrt{5}+1=-\sqrt{5}-1\\ Sửa:C=\sin^225^0+\sin^250^0+\sin^265^0+\sin^240^0\\ C=\left(\sin^225^0+\sin^265^0\right)+\left(\sin^250^0+\sin^240^0\right)\\ C=\left(\sin^225^0+\cos^225^0\right)+\left(\sin^250^0+\cos^250^0\right)\\ C=1+1=2\)