Сократите дробь:
x^2-13x+40/x^2-25

x²-13x+40=x²-5x-8x+40=(x²-5x)-(8x-40)=x(x-5)-8(x-5)=(x-5)(x-8)x²-25=(x-5)(x+5)[(x-5)(x-8)] / [(x-5)(x+5)]=(x-8)/(x+5)