Question

324-упр. Алгебра 7-класс

Answer 1

Объяснение:

$1)(2m)(4n) - 3a(2b) - (0.2n)(5m) + b(5a) - 5nm + 8ab = 8nm - 6ab - nm + 5ab - 5nm + 8ab = nm(8 - 1 - 5) + ab( - 6 + 5 + 8) = 2nm + 7ab$

$2)13ab - 0.2xy - (2a)(5b) + (6x)(0.2y) + a( - 3)b = 13ab - 0.2xy - 10ab + 1.2xy - 3ab = ab(13 - 10 - 3) + xy( - 0.2 + 1.2) = xy$

$3)2abc5a + 1 \frac{5}{7} {a}^{2} \frac{7}{12} bc - 2 \frac{2}{3} ab( - \frac{3}{8} )a = 10 {a}^{2} bc + \frac{12 \times 7}{7 \times 12} {a}^{2} bc + \frac{8 \times 3}{3 \times 8} {a}^{2} bc = {a}^{2} bc(10 + 1 + 1) = 12 {a}^{2} bc$

$4)3nmk4n - \frac{3}{8} nm2\frac{2}{3} nk + \frac{2}{9} {n}^{2} m( - 4 \frac{1}{2} )k = 12 {n}^{2} mk - \frac{3 \times 8}{8 \times 3} {n}^{2} mk - \frac{2 \times 9}{9 \times 2} {n}^{2} mk = {n}^{2} mk(12 - 1 - 1) = 10 {n}^{2} mk$