Срочно... Номер 18 (1 и 2), номер 19 (1 и 2)....

✓4.18
1)
$(4 - 3 \sqrt{x} )(4 + 3 \sqrt{x} ) - 4x = {4}^{2} - {(3 \sqrt{x)} }^{2} - 4x = 16 - 9x - 4x = 16 - 13x$
2)
$(5 - \sqrt{2x} )(5 + \sqrt{2x} ) - (4x - 20) = 25 - 2x - 4x + 20 = 45 - 6x$
✓4.19
1)
$\sqrt{ {(x + 1)}^{2} - 4x } = \sqrt{ {x}^{2} + 2x + 1 - 4x} = \sqrt{ {x}^{2} - 2x + 1} = \sqrt{ {(x - 1)}^{2} } = |x - 1|$
2)
$\sqrt{ {(x - 3)}^{2} + 12x} = \sqrt{ {x}^{2} - 6x + 9 + 12x } = \sqrt{ {x}^{2} + 6x + 9 } = \sqrt{ {(x + 3)}^{2} } = |x + 3|$