5.3
5.4
100

(x-2)(x+7)

x(x) + 7x - 2x - 2(7)

x2 + 7x - 2x - 14

= x2 + 5x - 14

100

(8x3 - 12x) / (4x2)

4x(2x2 - 3) / 4x2

= 2x2 - 3 / x

200

(6x-7)(2x+5)

(6x(2x)) + (6x(5)) - (7(2x)) - 7(5)

12x2 + 30x - 14x - 35

= 12x2 + 16x - 35

200

5x2 + 2x + 3 / x+2

= 5x - 8 + 19/x+2

300

(x+ 6x - 5)(4x + 2)

x2(4x+2) + 6x(4x+2) - 5(4x+2)

4x+ 2x2 + 24x2 + 12x - 20x - 10 

= 4x3 + 26x2 - 8x - 10

300

(4x2 - 2x) / (-x)

4x2/-x - 2x/-x

= -4x + 2