Răspuns:
[tex]a)45 {x}^{3} y - 9x {y}^{2} = 9xy(5 {x}^{2} - y)[/tex]
[tex]b) {4a}^{2} - 12ab + 9 {b}^{2} = (2a - 3b) ^{2} [/tex]
[tex]c)(8x - 7) ^{2} - ({7x + 3})^{2} = (64 {x}^{2} - 2 \times 8x \times 7 + 49) - (49 {x}^{2} + 2 \times 7x \times 3 + 9) = (64 {x}^{2} - 112x + 49) - (49 {x}^{2} + 42x + 9) = 64 {x}^{2} - 112x + 49 - {49x}^{2} - 42x - 9 = 15 {x}^{2} - 154x + 40[/tex]
