Question

2xy(x² +xy-3y²)

b) (x+2)(3x²-4x)
C) (x³+3x²-8x-20):(x+2)
d) (4x²-4x-4);(x+4)
e) (2x³-3x²+x-2):(x+5)
F) (x+y)²+(x-y)²-2(x+y)(x-y)
g) (a+b)³-(a-b)³ -2b³
h) (x-y)(x+y)(x²+y²)(x⁴+y4)
i)2x²(x-2)+3x(x²-x-2)-5(3-x²⁾
I) (x⁴-x³-3x²+x+2):(x²-1)
bài 2
thực hiện phép tính
\(\dfrac{x}{x-3}\)+\(\dfrac{9-6x}{x^2-3x}\)
b) \(\dfrac{6x-3}{x}\):\(\dfrac{4x^2-1}{3x_{ }^2}\)
c) \(\dfrac{x+2}{3x}+\dfrac{x-5}{5x}-\dfrac{x+8}{4x}\)
d) \(\dfrac{x^2-x+1}{x^2+x}.\dfrac{x+1}{3x-2}.\dfrac{9x-6}{x^2-x+1}\)
bài 3 cho hình bình hành ABCD có AD= 2.AB , Góc A =60 độ.Gọi E,F lần lượt là trung điểm của BC và AD
CHứng minh : AE\(\perp\)BF
b) BFDC là hình thang cân
c) tính ADB
d) lấy M đối xứng với A qua B .Cminh tứ giác BMCD là hình chữ nhật .SUy ra M,E,D thẳng hàng

Answer 1

Đăng ít thôi.

Answer 2

Bài 2:

a) \(\dfrac{x}{x-3}+\dfrac{9-6x}{x^2-3x}\)

\(=\dfrac{x}{x-3}+\dfrac{9-6x}{x\left(x-3\right)}\)

\(=\dfrac{x^2-6x+9}{x\left(x-3\right)}\)

\(=\dfrac{\left(x-3\right)^2}{x\left(x-3\right)}\)

\(=\dfrac{x-3}{x}\)

b) \(\dfrac{6x-3}{x}:\dfrac{4x^2-1}{3x^2}\)

\(=\dfrac{6x-3}{x}.\dfrac{3x^2}{4x^2-1}\)

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

\(=\dfrac{9x}{2x+1}\)

c) \(\dfrac{x+2}{3x}+\dfrac{x-5}{5x}-\dfrac{x+8}{4x}\)

\(=\dfrac{20x\left(x+2\right)+12x\left(x-5\right)-15x\left(x+8\right)}{60x}\)

\(=\dfrac{20x^2+40x+12x^2-60x-15x^2-120x}{60x}\)

\(=\dfrac{17x^2-140x}{60x}\)

d) \(\dfrac{x^2-x+1}{x^2+x}.\dfrac{x+1}{3x-2}.\dfrac{9x-6}{x^2-x+1}\)

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

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

\(=\dfrac{3}{x}\).