2x^2 + x - 6
7x^2 + 50x +7
12x^2 + 7x - 12
15x^2 + 7x - 2
a^2 - 5a - 14
4p^2 - 36p + 56
2x^2 + 5x +2
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Những câu hỏi liên quan
TG
4 tháng 8 2020
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/ \(4p^2-36p+56\)
\(=4p^2-28p-8p+56\)
\(=4p\left(p-7\right)-8\left(p-7\right)\)
\(=\left(p-7\right)\left(4p-8\right)\)
TT
4
NC
27 tháng 8 2020
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) \(7x^2-50x+7=0\Leftrightarrow\left(x-7\right)\left(7x-1\right)=0\)
\(\Leftrightarrow\orbr{\begin{cases}x-7=0\\7x-1=0\end{cases}}\Leftrightarrow\orbr{\begin{cases}x=7\\x=\frac{1}{7}\end{cases}}\)
27 tháng 8 2020
-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
<=> \(\orbr{\begin{cases}7x-1=0\\x-7=0\end{cases}}\Leftrightarrow\orbr{\begin{cases}x=\frac{1}{7}\\x=7\end{cases}}\)
28 tháng 12 2021
\(a,=\left(6x^3+3x^2-10x^2-5x+4x+2\right):\left(2x+1\right)\\ =\left[3x^2\left(2x+1\right)-5x\left(2x+1\right)+2\left(2x+1\right)\right]:\left(2x+1\right)\\ =3x^2-5x+2\\ b,Sửa:\left(2x^3-21x^2+67x-60\right):\left(x-5\right)\\ =\left(2x^3-10x^2-11x^2+55x+12x-60\right):\left(x-5\right)\\ =\left[2x^2\left(x-5\right)-11x\left(x-5\right)+12\left(x-5\right)\right]:\left(x-5\right)\\ =2x^2-11x+12\)
19 tháng 8 2019
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)
19 tháng 8 2019
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.
23 tháng 10 2018
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)
17 tháng 10 2018
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)
17 tháng 10 2018
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
2x^2 + x - 6
= 2x^2 + 4x - 3x - 6
= 2x(x + 2) - 3(x + 2)
= (2x - 3)(x + 2)
7x^2 + 50x + 7
= 7x^2 + x + 49x + 7
= 7x(x + 7) + x + 7
= (7x + 1)(x + 7)
12x^2 + 7x - 12
15x^2 + 7x - 2
= 15x^2 - 3x + 10x - 2
= 3x(5x - 1) + 2(5x - 1)
= (3x + 2)(5x - 1)
a^2 - 5a - 14
= a^2 + 2a - 7a - 14
= a(a + 2) - 7(a + 2)
= (a - 7)(a + 2)
2x^2 + 5x + 2
= 2x^2 + x + 4x + 2
= 2x(x + 2) + x + 2
= (2x + 1)(x + 2)
\(2x^2+x-6=2x^2+4x-3x-6\)
\(=2x\left(x+2\right)-3\left(x+2\right)\)
\(=\left(x+2\right)\left(2x-3\right)\)
\(7x^2+50x+7\)
\(=7x^2+x+49x+7\)
\(=x\left(7x+1\right)+7\left(7x+1\right)\)
\(=\left(7x+1\right)\left(x+7\right)\)
\(12x^2+7x-12\)
\(=12x^2+16x-9x-12\)
\(=4x\left(3x+4\right)-3\left(3x+4\right)\)
\(=\left(3x+4\right)\left(4x-3\right)\)