( x - 6 )2 - 9 = 0
x(x+1)<0
(x-6)(x+4)<0
(x+6)(2x+4)>0
(x^2+1)(x-9)>0
(x^2-7)(x^2-12)<0
(x^2-9)(x^2-4)<0
Dễ mà,e cứ chia 2 TH là đc
Vd:<0 thì chia ra x+2>0 hoac x<0 và nguoc lai roi tìm x
Tính nhẩm :
9 x 1 =
9 x 5 =
9 x 4 =
9 x 10 =
9 x 2 =
9 x 7 =
9 x 8 =
9 x 0 =
9 x 3 =
9 x 9 =
9 x 6 =
0 x 9 =
9 x 1 = 9
9 x 5 = 45
9 x 4 = 32
9 x 10 = 90
9 x 2 = 18
9 x 7 = 63
9 x 8 = 72
9 x 0 = 0
9 x 3 = 27
9 x 9 = 81
9 x 6 = 54
0 x 9 = 0
= 9 = 45 = 36
Tính nhẩm :
9 x 4 =
9 x 2 =
9 x 5 =
9 x 10 =
9 x 1 =
9 x 7 =
9 x 8 =
0 x 9 =
9 x 3 =
9 x 6 =
9 x 9 =
9 x 0 =
9 x 4 = 36
9 x 2 = 18
9 x 5 = 40
9 x 10 = 90
9 x 1 = 9
9 x 7 = 63
9 x 8 = 72
0 x 9 = 0
9 x 3 = 27
9 x 6 = 54
9 x 9 = 81
9 x 0 = 0
Tính nhẩm.
a) 9 x 1 9 x 4 9 x 7
b) 9 x 2 9 x 5 9 x 8
c) 9 x 3 9 x 6 9 x 9
d) 9 x 10 9 x 0 0 x 9
a) 9 x 1=9 9 x 4=36 9 x 7=63
b) 9 x 2=18 9 x 5=45 9 x 8=72
c) 9 x 3=27 9 x 6=54 9 x 981
d) 9 x 10=90 9 x 0=0 0 x 9=0
1) (x+6)(3x-1)+x+6=0
2) (x+4)(5x+9)-x-4=0
3)(1-x)(5x+3)÷(3x-7)(x-1)
4)2x (2x-3)=(3-2x)(2-5x)
5)(2x-7)^2-6(2x-7)(x-3)=0
6)(x-2)(x+1)=x^2-4
7) x^2-5x+6=0
8)2x^3+6x^2=x^2+3x
9)(2x+5)^2=(x+2)^2
1) (x+6)(3x-1)+x+6=0
⇔(x+6)(3x-1)+(x+6)=0
⇔(x+6)(3x-1+1)=0
⇔3x(x+6)=0
2) (x+4)(5x+9)-x-4=0
⇔(x+4)(5x+9)-(x+4)=0
⇔(x+4)(5x+9-1)=0
⇔(x+4)(5x+8)=0
3)(1-x)(5x+3)÷(3x-7)(x-1)
=\(\frac{\left(1-x\right)\left(5x+3\right)}{\left(3x-7\right)\left(x-1\right)}=\frac{\left(1-x\right)\left(5x+3\right)}{\left(7-3x\right)\left(1-x\right)}=\frac{\left(5x+3\right)}{\left(7-3x\right)}\)
2.4 Rút gọn biểu thức
\(a,\dfrac{3-\sqrt{x}}{x-9}\) ( vs x ≥ 0, x≠ 9)
b, \(\dfrac{x-5\sqrt{x}+6}{\sqrt{x}-3}\)( vs x ≥ 0 ; x ≠ 9)
c, \(6-2x-\sqrt{9-6x+x^2}\left(x< 3\right)\)
a) \(\dfrac{3-\sqrt{x}}{x-9}=\dfrac{-\left(\sqrt{x}-3\right)}{\left(\sqrt{x}-3\right)\left(\sqrt{x}+3\right)}=-\dfrac{1}{\sqrt{x+3}}\)(\(x\ge0,x\ne9\))
b) \(\dfrac{x-5\sqrt{x}+6}{\sqrt{x}-3}=\dfrac{\left(\sqrt{x}-3\right)\left(\sqrt{x}-2\right)}{\sqrt{x}-3}=\sqrt{x}-2\left(x\ge0,x\ne9\right)\)
a) \(\dfrac{3-\sqrt{x}}{x-9}=\dfrac{3-\sqrt{x}}{\left(\sqrt{x}-3\right)\left(\sqrt{x}+3\right)}=-\dfrac{1}{\sqrt{x}+3}\)
b) \(\dfrac{x-5\sqrt{x}+6}{\sqrt{x}-3}=\dfrac{\left(\sqrt{x}-2\right)\left(\sqrt{x}-3\right)}{\sqrt{x}-3}=\sqrt{x}-2\)
c) \(6-2x-\sqrt{9-6x+x^2}=6-2x-\sqrt{\left(3-x\right)^2}=6-2x-\left|3-x\right|\)
mà \(x< 3\Rightarrow3-x>0\Rightarrow6-2x-\left|3-x\right|=6-2x-3+x=3-x\)
a,\(\dfrac{3-\sqrt{x}}{x-9}\)
=\(-\dfrac{3-\sqrt{x}}{\left(3-\sqrt{x}\right)\left(3+\sqrt{x}\right)}\)
=\(-\dfrac{1}{3+\sqrt{x}}\)
Tính nhẩm
6 x 1 = ..... 6 x 9 = .....
6 x 2 = ..... 6 x 8 = .....
6 x 3 = ..... 6 x 7 = .....
6 x 4 = ..... 0 x 6 = .....
6 x 5 = ..... 6 x 0 = .....
6 x 6 = ..... 6 x 10 = .....
6 x 1 = 6 6 x 9 = 54
6 x 2 = 12 6 x 8 = 48
6 x 3 = 18 6 x 7 = 42
6 x 4 = 24 0 x 6 = 0
6 x 5 = 30 6 x 0 = 0
6 x 6 = 36 6 x 10 = 60
Tính nhẩm:
6 x 4 =
6 x 1 =
6 x 9 =
6 x 10 =
6 x 6 =
6 x 3 =
6 x 2 =
0 x 6 =
6 x 8 =
6 x 5 =
6 x 7 =
6 x 0 =
6 x 4 =24
6 x 1 =6
6 x 9 =54
6 x 10 =60
6 x 6 =36
6 x 3 =18
6 x 2 =12
0 x 6 =0
6 x 8 =48
6 x 5 =30
6 x 7 =42
6 x 0 =0
1) (3x-6)(x+5)+4(x-2)=0
2) 3(x-5)(2x+9)+3x-15=0
3) (x2-16)(12-4x)=0
4) (9-x2)(4x-8)=0
5) (8-x3)(5x-125)=0
6) 4x=8
giúp mik kiểm tra 2 câu này vs
a) (x+1)(x+9)=(x+3)(x+5)
<=>x^2+10x+9=x^2+8x+15
<=>x^2+10x+9-x^2-8x-15=0
<=>9x-6=0
<=>9x=6
<=>x=6/9=2/3 => S= 2/3
d) (3x+5)(2x+1)=(6x-2)(x-3)
<=>6x^2+13x+5=6x^2-16x+6
<=>6x^2+13x+5-6x^2+16x-6=0
<=>29x-1=0
<=>29x=1
<=>x=1/29
a,
đoạn 9x-6-> 2x-6=0
=> x=3
b,6x^2+13x+5=6x^2-20x+6
33x=1
=>x=1/33
a) (x+1)(x+9)=(x+3)(x+5)
<=>x^2+10x+9=x^2+8x+15
<=>x^2+10x+9-x^2-8x-15=0
<=>9x-6=0 phải là 2x - 6
<=>9x=6
<=>x=6/9=2/3 => S= 2/3
d) (3x+5)(2x+1)=(6x-2)(x-3)
<=>6x^2+13x+5=6x^2-16x+6 phải là 6x^2 - 20x + 6
<=>6x^2+13x+5-6x^2+16x-6=0
<=>29x-1=0
<=>29x=1
<=>x=1/29
a) \(\left(x+1\right)\left(x+9\right)=\left(x+3\right)\left(x+5\right)\)
\(\Leftrightarrow x^2+10x+9=x^2+8x+15\)
\(\Leftrightarrow x^2+10x+9-x^2-8x-15=0\)
\(\Leftrightarrow2x-6=0\)
\(\Leftrightarrow x=3\)
Vây tập nghiệm của phương trình là \(S=\left\{3\right\}\)
d) \(\left(3x+5\right)\left(2x+1\right)=\left(6x-2\right)\left(x-3\right)\)
\(\Leftrightarrow6x^2+13x+5=6x^2-20x+6\)
\(\Leftrightarrow6x^2+13x+5-6x^2+20x-6=0\)
\(\Leftrightarrow33x-1=0\)
\(\Leftrightarrow x=\frac{1}{33}\)
Vây tập nghiệm của phương trình là \(S=\left\{\frac{1}{33}\right\}\)