Toán Lớp 8: helpppppppppppppppppppppppppppppppppppppppppp
a) $\frac{35(x^{2}-y^{2})(x+y)^{2}}{77(y-x)^{2}(x+y)^{3}}$
b) $\frac{4x^{2}y^{2}+1-4xy}{8x^{3}y^{3}-1-6xy(2xy-1)}$
c) $\frac{x^{2}-xy-xz+z}{x^{2}+xy-xz-yz}$
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Toán Lớp 8: helpppppppppppppppppppppppppppppppppppppppppp
a) $\frac{35(x^{2}-y^{2})(x+y)^{2}}{77(y-x)^{2}(x+y)^{3}}$
b) $\frac{4x^{2}y^{2}+1-4xy}{8x^{3}y^{3}-1-6xy(2xy-1)}$
c) $\frac{x^{2}-xy-xz+z}{x^{2}+xy-xz-yz}$
Comments ( 2 )
$a,$ $\dfrac{35(x^2-y^2)(x+y)^2}{77(y-x)^2(x+y)^3}$
$=\dfrac{35(x-y)(x+y)(x+y)^2}{77(x-y)^2(x+y)^3}$
$=\dfrac{35(x+y)}{77(x-y)(x+y)}$
$=\dfrac{35}{77(x-y)}$
$=\dfrac{7.5}{7.11(x-y)}$
$=\dfrac{5}{11(x-y)}$
$b,$ $\dfrac{4x^2y^2+1-4xy}{8x^3y^3-1-6xy(2xy-1)}$
$=\dfrac{(2xy)^2-4xy+1}{8x^3y^3-1-12x^2y^2+6xy}$
$=\dfrac{(2xy-1)^2}{8x^3y^3-12x^2y^2+6xy-1}$
$=\dfrac{(2xy-1)^2}{(2xy-1)^3}$
$=\dfrac{1}{2xy-1}$
$c,$ Sửa: $\dfrac{x^2-xy-xz+zy}{x^2+xy-xz-yz}$
$=\dfrac{x(x-y)-z(x-y)}{x(x+y)-z(x+y)}$
$=\dfrac{(x-z)(x-y)}{(x-z)(x+y)}$
$=\dfrac{x-y}{x+y}$
Giải đáp:
$\begin{array}{l} a. \quad \dfrac{5}{11(x-y)} \\ b. \quad\dfrac{1}{2xy-1} \\c . \quad \dfrac{x-y}{x+y} \end{array}$
Lời giải và giải thích chi tiết:
a/
$\dfrac{35(x^2 -y^2)(x+y)^2}{77(y-x)^2(x+y)^3}$
= (35(x-y)(x+y)(x+y)^2)/(77(x-y)^2(x+y)^3)
= 5/(11(x-y))
b/
(4x^2y^2+1-4xy )/(8x^3y^3 -1-6xy(2xy-1))
= ( (2xy-1)^2)/( (2xy-1)(4x^2y^2 +2xy +1) – 6xy(2xy-1))
= ( (2xy-1)^2)/( (2xy-1)(4x^2y^2 -4xy+1))
= ( (2xy-1)^2)/( (2xy-1)(2xy-1)^2)
= 1/(2xy-1)
c/
(x^2 -xy-xz+zy)/(x^2+xy -xz -yz)
= ( x(x-y) – z(x-y) )/( x(x+y) – z(x+y))
= ( (x-z)(x-y))/((x-z)(x+y))
= (x-y)/(x+y)