1)K = xx -49 -(x+7)(2x-3)
= xx - 49 -(2xx-3x+14x-21)
= xx-49 -(2xx+11x-21)
= xx -49 -2xx -11x + 21
= -xx -11x -28
2) xx - 49 = xx -7x7
= (x-7)(x+7)
b. on sait que K= xx-49 - (x+7)(2x-3)
= (x-7)(x+7) - (x-7) (2x-3)
= (x-7) (x+7 -2x +3 )
= (x-7) (-x + 10)
3) k= (x-7) (-x+10)
= (-4-7)(-(-4)+10)
= -11 x 14
= -154