Question

rút gọn
a) 7x^2 +14x +7/ 3x^2 + 3x
b) 2a^2 - 20ab / ac + ad - bc - bd
c) x^2 - xy / y^2 - x^2

Answer 1

\(a,\dfrac{7x^2+14x+7}{3x^2+3x}=\dfrac{7\left(x^2+2x+1\right)}{3x\left(x+1\right)}=\dfrac{7\left(x+1\right)^2}{3x\left(x+1\right)}=\dfrac{7x+7}{3x}\)

\(b,\dfrac{2a^2-2ab}{ac+ad-bc-bd}=\dfrac{2a\left(a-b\right)}{a\left(c+d\right)-b\left(c+d\right)}=\dfrac{2a\left(a-b\right)}{\left(a-b\right)\left(c+d\right)}=\dfrac{2a}{c+d}\)

\(c,\dfrac{x^2-xy}{y^2-x^2}=\dfrac{x\left(x-y\right)}{-\left(x-y\right)\left(x+y\right)}=\dfrac{x}{-x-y}\)

Answer 2

a) \(\dfrac{7x^2+14x+7}{3x^2+3x}=\dfrac{7\left(x^2+2x+1\right)}{3x\left(x+1\right)}\)

\(=\dfrac{7\left(x+1\right)^2}{3x\left(x+1\right)}=\dfrac{7\left(x+1\right)}{3x}\)

b) \(\dfrac{2a^2-2ab}{ac+ad-bc-bd}=\dfrac{2a\left(a-b\right)}{a\left(c+d\right)-b\left(c+d\right)}\) ( có sửa đề )

\(=\dfrac{2a\left(a-b\right)}{\left(c+d\right)\left(a-b\right)}=\dfrac{2a}{c+d}\)

c) \(\dfrac{x^2-xy}{y^2-x^2}=\dfrac{-x\left(x-y\right)}{\left(x-y\right)\left(x+y\right)}\)

\(=\dfrac{-x}{\left(x+y\right)}\)