B3. 2) (2x²+3x)/(x² -9) -x²/(x² -9), при х=0.5
=(2x²+3x -x²) /(x² -9) =(x²+3x )/(x² -9) =x(x+3) /(x+3)(x-3) =x/(x-3) =0.5 /(0.5-3) = -0.2
B4. 2) (4x² -1) /(x²+2x+1) -3x² /(x²+2x+1), при х=1/3
=(4x² -1 -3x²) /(x²+2x+1) =(x²-1) /(x+1)² =(x-1)(x+1) /(x+1)² =(x-1) /(x+1) =(1/3 -1) /(1/3 +1) = -0.5