b: \(\Leftrightarrow\left(x^2+3x+2\right)\left(x^2+3x-18\right)=-36\)

\(\Leftrightarrow\left(x^2+3x\right)^2-16\left(x^2+3x\right)=0\)

\(\Leftrightarrow\left(x^2+3x\right)\left(x^2+3x-16\right)=0\)

hay \(x\in\left\{0;-3;\dfrac{-3+\sqrt{73}}{2};\dfrac{-3-\sqrt{73}}{2}\right\}\)

c: \(\Leftrightarrow6x^4-18x^3-17x^3+51x^2+11x^2-33x-2x+6=0\)

\(\Rightarrow\left(x-3\right)\left(6x^3-17x^2+11x-2\right)=0\)

\(\Leftrightarrow\left(x-3\right)\left(6x^3-12x^2-5x^2+10x+x-2\right)=0\)

\(\Leftrightarrow\left(x-3\right)\left(x-2\right)\left(6x^2-5x+1\right)=0\)

\(\Leftrightarrow\left(x-3\right)\left(x-2\right)\left(3x-1\right)\left(2x-1\right)=0\)

hay \(x\in\left\{3;2;\dfrac{1}{3};\dfrac{1}{2}\right\}\)

d: \(\Leftrightarrow\left(x-1\right)^2\cdot\left(x^2+3x+1\right)=0\)

hay \(x\in\left\{1;\dfrac{-3+\sqrt{5}}{2};\dfrac{-3-\sqrt{5}}{2}\right\}\)

câu b nè : http://123link.pw/fGAhMX

a: \(\dfrac{x+10}{4x-8}\cdot\dfrac{4-2x}{x+2}\)

\(=\dfrac{x+10}{4\left(x-2\right)}\cdot\dfrac{-2\left(x-2\right)}{x+2}=\dfrac{-\left(x+10\right)}{2\left(x+2\right)}\)

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

\(=\dfrac{\left(2x-1\right)\left(2x+1\right)}{x\left(x+4\right)}\cdot\dfrac{3x}{2\left(x-2\right)}\)

\(=\dfrac{3\left(2x-1\right)\left(2x+1\right)}{2\left(x-2\right)\left(x+4\right)}\)

c: \(=\dfrac{4y^2}{7x^4}\cdot\dfrac{35x^2}{-8y}=\dfrac{5}{x^2}\cdot\dfrac{-1}{2}\cdot y=\dfrac{-5y}{2x^2}\)

d: \(=\dfrac{\left(x-2\right)\left(x+2\right)}{3\left(x+4\right)}\cdot\dfrac{x+4}{2\left(x-2\right)}=\dfrac{x+2}{6}\)

a) 2459 - ( 400 + 459 )

= ( 2459 - 459 ) - 400

= 2000 - 400

= 1600

b) 435 x 25 + 75 x 435

= 435 x ( 75 + 25 )

= 435 x 100

= 43 500

c) 35 x 49 + 51 x 35

= 35 x ( 49 + 51 )

= 35 x 100

= 3500

z mak p k bít uk

wá dễ

a) =1600

b) =43 500

c) =3500

\(f\left(x\right)=x^3-9x^2-35x+7=x^2\left(x-12\right)+3x\left(x-12\right)+\left(x-12\right)+19\)

số dư: 19

p/s: có thể thay trực tiếp f(12)=m =số dư

3x² + x - 10 = 0

<=> (x + 2)(3x - 5) = 0

\(\Leftrightarrow\left[{}\begin{matrix}x=-2\\x=\dfrac{5}{3}\end{matrix}\right.\)

2x² - x - 15 = 0

<=> (x - 3)(2x + 5) = 0

\(\Leftrightarrow\left[{}\begin{matrix}x=3\\x=-\dfrac{5}{2}\end{matrix}\right.\)

7x² + 23x - 20 = 0

<=> (7x - 5)(x + 4) = 0

\(\Leftrightarrow\left[{}\begin{matrix}x=\dfrac{5}{7}\\x=-4\end{matrix}\right.\)

6x² - 35x + 25 = 0

<=> (x - 5)(6x - 5) = 0

\(\Leftrightarrow\left[{}\begin{matrix}x=5\\x=\dfrac{5}{6}\end{matrix}\right.\)

6x² - x - 2 = 0

<=> (3x - 2)(2x + 1) = 0

\(\Leftrightarrow\left[{}\begin{matrix}x=\dfrac{2}{3}\\x=-\dfrac{1}{2}\end{matrix}\right.\)

8x² + 6x - 35 = 0

<=> (4x - 7)(2x + 5) = 0

\(\Leftrightarrow\left[{}\begin{matrix}x=\dfrac{7}{4}\\x=-\dfrac{5}{2}\end{matrix}\right.\)

\(2x^3-35x+75=2x^2\left(x+5\right)-10x\left(x+5\right)+15\left(x+5\right)=\left(x-5\right)\left(2x^2-10+15\right) \)

c/ \(x^5+x^4+x^3+x^2+x+1\)

= \(\left(x^5+x^4\right)+\left(x^3+x^2\right)+\left(x+1\right)\)

= \(x^4\left(x+1\right)+x^2\left(x+1\right)+\left(x+1\right)\)

=\(\left(x+1\right)\left(x^4+x^2+1\right)\)

\(x^6-9x^3+8\)

\(=x^2\left(x^4-2x^3-x+2\right)+2x\left(x^4-2x^3-x+2\right)+4\left(x^4-2x^3-x+2\right)\)

\(=\left(x^4-2x^3-x+2\right)\left(x^2+2x+4\right)\)

\(=\left(x^2-3x+2\right)\left(x^2+x+1\right)\left(x^2+2x+4\right)\)

\(=\left(x-2\right)\left(x-1\right)\left(x^2+x+1\right)\left(x^2+2x+4\right)\)

a) \(37\times46+37\times51+111\)

\(=37\times46+37\times51+37\times3\)

\(=37\times\left(46+51+3\right)\)

\(=37\times100\)

\(=3700\)

b) \(35\times215-35\times210-175\)

\(=35\times215-35\times210-35\times5\)

\(=35\times\left(215-210-5\right)\)

\(=35\times0\)

\(=0\)

c) \(172\times47+86\times8-34\times4\)

\(=4\times\left(43\times47+86\times2-34\right)\)

\(=4\times\left(2021+172-34\right)\)

\(=4\times2159\)

\(=8636\)

d) \(48\times56+28\times104\)

\(=48\times56+56\times52\)

\(=56\times\left(48+52\right)\)

\(=56\times100\)

\(=5600\)