Question

докажите торжество б) (х-а) (х-b)=х^2- (a+b) х + ab

Answer 1

$(x - a)(x - b) = x^2 - (a + b)x + ab \ x^2 - xb - ax + ab = x^2 - (a + b)x + ab \ x^2- x(a + b) + ab = x^2 - (a + b)x + ab \ x^2- x(a + b) + ab - x^2+ x(a + b) - ab = 0 \ 0 = 0$