Question

bỏ dấu ngoặc rồi viết gọn những biểu thức sau:

a, x(a-b)-x(a+b)

b, (\(a^2\)-ax+by)-(by- \(a^2\) -ax)

c,(a-b)(a+b)-(b-a).b

Answer 1

Lời giải:

a)
$x(a-b)-x(a+b)=xa-xb-xa-xb=-2xb$

b)

$(a^2-ax+by)-(by-a^2-ax)=a^2-ax+by-by+a^2+ax=2a^2$

c)

$(a-b)(a+b)-(b-a)b=a^2-b^2-(b^2-ab)=a^2-b^2-b^2+ab=a^2-2b^2+ab$

Answer 2

\(a,x\left(a-b\right)-x\left(a+b\right)\)

\(=ax-bx-ax-bx=-2bx\)

\(b,\left(a^2-ax+by\right)-\left(by-a^2-ax\right)\)

\(=a^2-ax+by-by+a^2+ax=2a^2\)

\(c,\left(a-b\right)\left(a+b\right)-\left(b-a\right).b\)

\(=a^2-b^2-b^2+ab\)

\(=\left(a-b\right)^2-b^2=\left(a-b-b\right)\left(a-b+b\right)\)

\(=\left(a-2b\right).a\)