Question

Can anyone understand me this step?????plz plz......urgent....

Answer 1

here componendo n dividendo is used
a/b= a+b/a-b

Answer 2

${a}^{3} + {b}^{3} = (a + b)( {a}^{2} - ab + {b}^{2} ) \\ {a}^{3} - {b}^{3} = (a - b)( {a}^{2} + ab + {b}^{2} )$
According this formula