C = (2x+3)² -49
C = (2x² +2*2x*3+3²) -49
C = 2x² +12x +9 -49
C = 2x² +12x -40
D = (2-x)² - (4x+5)²
D = (2² -2*2*x+x²) - (4x² +2*4x*5 +5²)
D = 4-4x+x²-16x+40x+25
D = x²+20x+29
E = 25- (3x-1)²
E = 25- (3x² -2*3x*1+1²)
E = 25- 9x -6x +1
E = (-15x)+25
F = (4x +1)² - (7-2x)²
F = (4x² +2*4x*1+1²) - (7² -2*7*2x+2x²)
F = 16x +8x +1-49-98x +4x²
F = 4x² -74x -48