**(i) x ^{2}y^{2} – xy – 72**

**(ii) 9x ^{3}y + 41x^{2}y^{2} + 20xy^{3}**

**Answer :**

**(i) x**^{2}y^{2} – xy – 72

^{2}y

^{2}– xy – 72

x^{2}y^{2} – 9xy + 8xy – 72

Take out common in all terms,

xy(xy – 9) + 8(xy – 9)

(xy – 9) (xy + 8)

**(ii) 9x**^{3}y + 41x^{2}y^{2} + 20xy^{3}

^{3}y + 41x

^{2}y

^{2}+ 20xy

^{3}

9x^{3}y + 41x^{2}y^{2} + 20xy^{3}

Take out common in all terms,

xy(9x^{2} + 41xy + y^{2})

Above terms can be written as,

xy (9x^{2} + 36xy + 5xy + 20y^{2})

xy [9x(x + 4y) + 5y(x + 4y)]

xy (x + 4y) (9x + 5y)