a/ \(3x^2-5x-2\)

\(=3x^2-3x-2x-2\)

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

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

b/ \(2x^2+x-6\)

\(=2x^2+4x-3x-6\)

\(=2x\left(x+2\right)+3\left(x+2\right)\)

\(=\left(x+2\right)\left(2x+3\right)\)

c/ \(7x^2+50x+7\)

\(=7x^2+49x+x+7\)

\(=7x\left(x+7\right)+\left(x+7\right)\)

\(=\left(x+7\right)\left(7x+1\right)\)

d/ \(12x^2+7x-12\)

\(=12x^2-9x+16x-12\)

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

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

e/ \(15x^2+7x-2\)

\(=15x^2+10x-3x-2\)

\(=5x\left(3x+2\right)-\left(3x+2\right)\)

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

f/ \(a^2-5a-14\)

\(=a^2+2a-7a-14\)

\(=a\left(a+2\right)-7\left(a+2\right)\)

\(=\left(a+2\right)\left(a-7\right)\)

g/ \(2m^2+10m+8\)

\(=2m^2+2m+8m+8\)

\(=2m\left(m+1\right)+8\left(m+1\right)\)

\(=\left(m+1\right)\left(2m+8\right)\)

h/ \(4p^2-36p+56\)

\(=4p^2-28p-8p+56\)

\(=4p\left(p-7\right)-8\left(p-7\right)\)

\(=\left(p-7\right)\left(4p-8\right)\)

1) \(-4x^2+8x=0\Leftrightarrow-4x\left(x-2\right)=0\)

\(\Leftrightarrow\orbr{\begin{cases}x=0\\x-2=0\end{cases}}\Leftrightarrow\orbr{\begin{cases}x=0\\x=2\end{cases}}\)

2) \(\left(2x-4\right)\left(x+1\right)=0\Leftrightarrow\orbr{\begin{cases}2x-4=0\\x+1=0\end{cases}}\Leftrightarrow\orbr{\begin{cases}2x=4\\x=-1\end{cases}}\Rightarrow\orbr{\begin{cases}x=2\\x=-1\end{cases}}\)

3) \(x^2-5x-14=0\Leftrightarrow\left(x+2\right)\left(x-7\right)=0\)

\(\Leftrightarrow\orbr{\begin{cases}x+2=0\\x-7=0\end{cases}}\Rightarrow\orbr{\begin{cases}x=-2\\x=7\end{cases}}\)

4) \(3x^2-5x-2=0\Leftrightarrow\left(3x+1\right)\left(x-2\right)=0\)

\(\Leftrightarrow\orbr{\begin{cases}3x+1=0\\x-2=0\end{cases}}\Leftrightarrow\orbr{\begin{cases}x=-\frac{1}{3}\\x=2\end{cases}}\)

5) xem lại đề

6) \(x^2-5x=0\)

\(\Leftrightarrow x\left(x-5\right)=0\)

\(\Leftrightarrow\orbr{\begin{cases}x=0\\x-5=0\end{cases}}\Leftrightarrow\orbr{\begin{cases}x=0\\x=5\end{cases}}\)

7) \(7x^2-50x+7=0\Leftrightarrow\left(x-7\right)\left(7x-1\right)=0\)

\(\Leftrightarrow\orbr{\begin{cases}x-7=0\\7x-1=0\end{cases}}\Leftrightarrow\orbr{\begin{cases}x=7\\x=\frac{1}{7}\end{cases}}\)

-4x² + 8x

Đa thức có nghiệm <=> -4x² + 8x = 0

                                <=> -4x( x - 2 ) = 0

                                <=> \(\orbr{\begin{cases}-4x=0\\x-2=0\end{cases}}\Leftrightarrow\orbr{\begin{cases}x=0\\x=2\end{cases}}\)

( 2x - 4 )( x + 1 )

Đa thức có nghiệm <=> ( 2x - 4 )( x + 1 ) = 0

                                <=> \(\orbr{\begin{cases}2x-4=0\\x+1=0\end{cases}}\Leftrightarrow\orbr{\begin{cases}x=2\\x=-1\end{cases}}\)

x² - 5x - 14

Đa thức có nghiệm <=> x² - 5x - 14 = 0

                                <=> x² + 2x - 7x - 14 = 0

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

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

                                <=> \(\orbr{\begin{cases}x+2=0\\x-7=0\end{cases}}\Leftrightarrow\orbr{\begin{cases}x=-2\\x=7\end{cases}}\)

3x² - 5x - 2

Đa thức có nghiệm <=> 3x² - 5x - 2 = 0

                               <=> 3x² + x - 6x - 2 = 0

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

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

                               <=> \(\orbr{\begin{cases}3x+1=0\\x-2=0\end{cases}}\Leftrightarrow\orbr{\begin{cases}x=-\frac{1}{3}\\x=2\end{cases}}\)

Chỗ này đề lỗi

x² - 5x

Đa thức có nghiệm <=> x² - 5x = 0

                                <=> x( x - 5 ) = 0

                                <=> \(\orbr{\begin{cases}x=0\\x-5=0\end{cases}}\Leftrightarrow\orbr{\begin{cases}x=0\\x=5\end{cases}}\)

7x² - 50x + 7

Đa thức có nghiệm <=> 7x² - 50x + 7 = 0

                               <=> 7x² - x - 49x + 7 = 0

                               <=> x( 7x - 1 ) - 7( 7x - 1 ) = 0

                               <=> ( 7x - 1 )( x - 7 ) = 0

                               <=> \(\orbr{\begin{cases}7x-1=0\\x-7=0\end{cases}}\Leftrightarrow\orbr{\begin{cases}x=\frac{1}{7}\\x=7\end{cases}}\)

thanks FL.Diversity SO MUCH

nh mk ko bt tk điểm cho bạn  ntn xin lỗi nhá

\(a,=\left(6x^3+3x^2-10x^2-5x+4x+2\right):\left(2x+1\right)\\ =\left[3x^2\left(2x+1\right)-5x\left(2x+1\right)+2\left(2x+1\right)\right]:\left(2x+1\right)\\ =3x^2-5x+2\\ b,Sửa:\left(2x^3-21x^2+67x-60\right):\left(x-5\right)\\ =\left(2x^3-10x^2-11x^2+55x+12x-60\right):\left(x-5\right)\\ =\left[2x^2\left(x-5\right)-11x\left(x-5\right)+12\left(x-5\right)\right]:\left(x-5\right)\\ =2x^2-11x+12\)

Bài 1: a) x² - 5x + 6 = x² - 2x - 3x + 6 = x(x - 2) - 3(x - 2) = (x - 3)(x - 2)

b) 3x² + 9x - 30 = 3x² + 15x - 6x - 30 = 3x(x + 5) - 6(x + 5) = (3x - 6)(x + 5) = 2(x - 2)(x + 5)

c) x² - 3x + 2 = x² - 2x - x + 2  = x(x - 2) - (x - 2) = (x - 1)(x - 2)

d) x² - 9x + 18 = x² - 3x - 6x + 18 = x(x - 3) - 6(x - 3) = (x - 6)(x - 3)

e) x² - 6x + 8 = x² - 2x - 4x + 8 = x(x - 2) - 4(x - 2) = (x - 4)(x - 2)

f) x² - 5x - 14 = x² - 7x + 2x - 14 = x(x - 7) + 2(x - 7) = (x + 2)(x - 7)

g) x² + 6x + 5 = x² + 5x + x + 5 = x(x + 5) + (x + 5) = (x + 1)(x + 5)

h) x² - 7x + 12 = x² - 3x - 4x + 12 = x(x - 3) -  4(x - 3) = (x - 4)(x - 3)

i) x² - 7x + 10 = x² - 2x - 5x + 10 = x(x - 2) - 5(x - 2) = (x - 5)(x - 2)

Oh Sehun:Ít một thôi bạn ơi!Làm xong đống này chắc đến tuổi già mất:(

a

\(x^2-5x+6\)

\(=\left(x^2-3x\right)-\left(2x-6\right)\)

\(=\left(x-3\right)\left(x-2\right)\)

b

\(3x^2+9x-30\)

\(=x^2+3x-10\)

\(=\left(x^2-2x\right)+\left(5x-10\right)\)

\(=\left(x-2\right)\left(x+5\right)\)

c

\(x^2-3x+2\)

\(=\left(x^2-x\right)-\left(2x-2\right)\)

\(=\left(x-1\right)\left(x-2\right)\)

d

\(x^2-9x+18\)

\(=\left(x^2-3x\right)-\left(6x-18\right)\)

\(=\left(x-3\right)\left(x-6\right)\)

e

\(x^2-6x+8\)

\(=\left(x^2-2x\right)-\left(4x-8\right)\)

\(=\left(x-2\right)\left(x-4\right)\)

f

\(x^2-5x-14\)

\(=\left(x^2+2x\right)-\left(7x+14\right)\)

\(=\left(x+2\right)\left(x-7\right)\)

g

\(x^2+6x+5\)

\(=\left(x^2+x\right)+\left(5x+5\right)\)

\(=\left(x+1\right)\left(x+5\right)\)

h

\(x^2-7x+12\)

\(=\left(x^2-3x\right)-\left(4x-12\right)\)

\(=\left(x-3\right)\left(x-4\right)\)

i

\(x^2-7x+10\)

\(=\left(x^2-2x\right)-\left(5x-10\right)\)

\(=\left(x-2\right)\left(x-5\right)\)

P/S:Cho e xin phép tách câu ạ.

Bài 2: a) xlđ

b) 2x² +  x  - 6 = 2x² + 4x - 3x - 6 = 2x(x + 2) - 3(x + 2) = (2x - 3)(x + 2)

c) 7x² + 50x + 7 = 7x² + x + 49x + 7 = x(7x + 1) + 7(7x + 1) = (x + 7)(7x + 1)

d) 12x² + 7x - 12 = 12x² + 16x - 9x - 12 = 4x(3x + 4) - 3(3x + 4) = (4x - 3)(3x + 4)

e) 15x² + 7x - 2 = 15x² + 10x - 3x - 2 =5x(3x + 2) - (3x + 2) = (5x - 1)(3x + 2)

f) a² - 5a - 14 = a² - 7a + 2a - 14 = a(a - 7) + 2(a - 7) = (a + 2)(a - 7_

g) 2m² + 10m + 8 = 2m² + 2m + 8m + 8 = 2m(m + 1) + 8(m + 1) = (2m + 8)(m + 1) = 2(m + 4)(m + 1)

h) 4p² - 36p + 56 = 4(p² - 9p + 14) = 4(p² - 2p - 7p + 14) = 4[p(p - 2) - 7(p - 2)] = 4(p - 7)(p - 2)

i) 2x² + 5x + 2 = 2x² + x + 4x + 2 = x(2x + 1) + 2(2x + 1) = (x + 2)(2x + 1)

giúp tôi nhanh với trưa nay là tôi phải làm rồi

a) 5x(10x+7)-25x(2x-3) = 40

50x²+35x-50x²+75x = 40

(50x²-50x²)+(35x+75x) = 40

110x = 40

x =\(\dfrac{40}{110}\)=\(\dfrac{4}{11}\)

b)

Bài 1: 

a: \(\Leftrightarrow50x^2+35x-50x^2+75x=40\)

=>110x=40

=>x=4/11

b: \(\Leftrightarrow3x^2-6x+2x-4-x^2+4x-3=4\)

=>2x^2-7=4

=>2x^2=11

=>x^2=11/2

hay \(x=\pm\sqrt{\dfrac{11}{2}}\)

Bài 2: 

a: \(=x+2ax-2ay-y\)

\(=x\left(1+2a\right)-y\left(2a+1\right)=\left(2a+1\right)\left(x-y\right)\)

b: \(=5a\left(a-x\right)-7\left(a-x\right)=\left(a-x\right)\left(5a-7\right)\)

Bài 2:

a) x + 2a.(x-y) - y

= 2a.(x-y) + (x-y)

= (x-y).(2a+1)

b) 5a² - 5ax - 7a + 7x

= 5a.(a-x) - 7.(a-x)

= (a-x).(5a-7)

Bài 1:

a) 5x.(10x+7) - 25x.(2x-3) = 40

50x² + 35x - 50x² + 75x = 40

110x = 40

x = 4/11

b) (3x+2).(x-2) - (x-1).(x-3) = 4

3x² - 6x + 2x - 4 - x² + 3x + x - 3 = 4

2x² - 7 = 4

...

bn tự làm tiếp nha

bạn giải thì giải đi công chúa ô ri