Разложить на множители квадратный трехчлен:

1) X^+17x-18

2) x^-20x-21

3) 5x^-13x-6

4) 3x^+x-10

^ - в квадрате

1) X^+17x-18 = X^+18x-x-18 = (x^-x) + (18x-18) = x (x-1) + 18 (x-1) = (x-1) (x+18)

2) x^-20x-21 = x^-21x+x-21 = (x^-21x) + (x-21) = x (x-21) + (x-21) = (x-21) (x+1)

3) 5x^-13x-6 = 5x^-15x+2x-6 = (5x^-15x) + (2x-6) = 5x (x-3) + 2 (x-3) = (x-3) (5x+2)

4) 3x^+x-10=3x^+6x-5x-10 = (3x^+6x) - (5x+10) = 3x (x+2) - 5 (x+2) = (x+2) (3x-5)