Tính giá trị:
\(A=\left(3,1-2,5\right)-\left(-2,5+3,1\right)\\
A=3,1-2,5+2,5-3,1\\
A=\left(3,1-3,1\right)-\left(2,5-2,5\right)\\
A=0\)
\(B=\left(5,3-2,8\right)-\left(4+5,3\right)\\
B=5,3-2,8-4-5,3\\
B=\left(5,3-5,3\right)-\left(2,8+4\right)\\
B=-6,8\)
\(C=-\left(251.3\right)+281+3.251-\left(1-281\right)\)
\(C=\left[-\left(251.3\right)+3.251\right]+\left[281-\left(1-281\right)\right]\\
C=0+560\\
C=560\)
\(D=-\left(\dfrac{3}{5}+\dfrac{3}{4}\right)-\left(-\dfrac{3}{4}+\dfrac{2}{5}\right)\\
D=-\dfrac{3}{5}-\dfrac{3}{4}+\dfrac{3}{4}-\dfrac{2}{5}\\
D=\left(-\dfrac{3}{5}-\dfrac{2}{5}\right)+\left(-\dfrac{3}{4}+\dfrac{3}{4}\right)\\
D=-1+0\\
D=-1\)