Giải bài 1 trang 16 SBT Toán 8 tập 1 CTST

a) $3x^{2} + 6xy = 3x.x + 3x.2y = 3x(x + 2y)$.

b) $5(y – 3) – x(3 – y)$

= $5(y – 3) + x(y ‒ 3)$

= $(y ‒ 3)(5 + x).$

c) $2x^{3} – 6x{2} = 2x^{2}.x‒ 2x^{2}.3 $

$= 2x^{2}(x ‒ 3)$.

d) $x^{4}y^{2} + xy^{3} = xy^{2}.x^{3} + xy^{2}.y $

$= xy^{2}(x^{3} + y)$.

e) $xy – 2xyz + x^{2}y$

= $xy ‒ xy.2z + xy.x$

= $xy(1 ‒ 2z + x)$.

g)$ (x + y)^{3} – x(x + y)^{2}$

= $(x + y)^{2}.(x + y) – x(x + y)^{2}$

= $(x + y)^{2 }(x + y ‒ x)$

= $y(x + y)^{2}$.