Ответ:

[tex]( \frac{ a}{b } - \frac{b}{a} ) \times 4 \times 1b - b[/tex]

[tex] \frac{a ^{2} - b {}^{2} }{ab} \times 4b - b[/tex]

[tex] \frac{a ^{2} - b {}^{2} }{a} \times 4 - b[/tex]

[tex] \frac{4(a ^{2} - b ^{2} )}{a} - b[/tex]

[tex] \frac{4a {}^{2} - 4b {}^{2} }{a} - b[/tex]

[tex] \frac{4a {}^{2} - 4b ^{2} - ab }{a} [/tex]