(x - 5) . (8 - x) > 0
Tính nhẩm
8 x 3 =
8 x 2 =
8 x 4 =
8 x 1 =
8 x 5 =
8 x 6 =
8 x 7 =
0 x 8 =
8 x 8 =
8 x 10 =
8 x 9 =
8 x 0 =
Học sinh tự nhẩm và ghi như sau:
8 x 3 = 24
8 x 2 = 16
8 x 4 = 32
8 x 1 = 8
8 x 5 = 40
8 x 6 = 48
8 x 7 = 56
0 x 8 = 0
8 x 8 = 64
8 x 10 = 80
8 x 9 = 72
8 x 0 = 0
1.24
2.16
3.32
4.8
5.40
6.48
7.56
8.0
9.64
10.80
11.72
12.0
a)|x+5|=|-x+5|
b)|3x+8|-|2x-70|=0
c)|x+1|+|y-8|=0
d)|x-y|+|y-5|+|x-y-z|=0
e)|x-y+5|+|x+y+1|=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
b. x( x – 4) - 2x + 8 = 0
c. x^2-25 –( x+5 ) = 0
d.(2x -1)^2- (4x2 – 1) = 0
e. ( 3x – 1)^2 – ( x +5)^2 = 0
f. x^3 – 8 – (x -2)(x -12) =0
b) x(x-4) - 2x+8 = 0
x(x-4) - 2(x-4) = 0
(x-2) (x-4) = 0
TH1: x-2=0 TH2: x-4=0
x=2 x=4
Vậy x\(\in\){2;4}
\(b,\Leftrightarrow\left(x-4\right)\left(x-2\right)=0\Leftrightarrow\left[{}\begin{matrix}x=2\\x=4\end{matrix}\right.\\ c,\Leftrightarrow\left(x-5\right)\left(x+5\right)-\left(x+5\right)=0\\ \Leftrightarrow\left(x+5\right)\left(x-6\right)=0\Leftrightarrow\left[{}\begin{matrix}x=6\\x=-5\end{matrix}\right.\\ d,\Leftrightarrow\left(2x-1\right)^2-\left(2x-1\right)\left(2x+1\right)=0\\ \Leftrightarrow\left(2x-1\right)\left(2x-1-2x-1\right)=0\\ \Leftrightarrow x=\dfrac{1}{2}\\ e,\Leftrightarrow\left(3x-1-x-5\right)\left(3x-1+x+5\right)=0\\ \Leftrightarrow\left(2x-6\right)\left(4x+4\right)=0\\ \Leftrightarrow\left[{}\begin{matrix}x=-1\\x=3\end{matrix}\right.\\ f,\Leftrightarrow\left(x-2\right)\left(x^2+2x+4\right)-\left(x-2\right)\left(x-12\right)=0\\ \Leftrightarrow\left(x-2\right)\left(x^2+x+16\right)=0\\ \Leftrightarrow\left[{}\begin{matrix}x=2\\\left(x+\dfrac{1}{2}\right)^2+\dfrac{63}{4}=0\left(vô.n_0\right)\end{matrix}\right.\\ \Leftrightarrow x=2\)
b) x(x-4)-2x+8=0
x(x-4)-2(x-4)=0
(x-4)(x-2)=0
th1: x-4=0
x=4
th2: x-2=0
x=2
Vậy x thuộc tập hợp 4;-2
Viết tập hợp các số nguyên:
a ) – 4 < x < 2 ; c ) − 8 ≤ x ≤ − 5 ; e ) – 7 < x < 0 ; b ) 0 < x ≤ 11 ; d ) − 5 ≤ x < 8 ; f ) 0 ≤ x < 1.
1. 13-(x-5)=8 8. (x-5)^6=(x-5)^8
2. 8-(x-10)=23-(-4+12) 9. (3-x).(x-3)=0
3. 134-5(x+4)=34 10. -32-(x-5)=0
4. |5-x|=7
5. 20+8.(x+3)=5^2.4
6. 42x=39.42-37.42
7. |x|=2-(-7)
1) 3(x-5)(2x+9)+3x-15=0
2) (x2-16)(12-4x)=0
3) (9-x2)(4x-8)=0
4) (8-x3)(5x-125)=0
5) 4x=8
1)=>3(x-5)(2x+9)+3(x-5)=0=>(x-5)(6x+30)
=>x-5=0=>x=5
6x+30=0=>x=-5
2)=>x^2-16=0=>x=+-4
12-4x=0=>x=3
3)=>9-x^2=0=>x=+-3
4x-8=0=>x=2
4)=>8-x^3=0=>x=3
5^x-125=0=>x=2
5)=>2^x.2^x=8=>2^2x=8=>2x=3=>x=1,5
Tìm x biết
a) -3.(x-4)+5.(x-1)=-7
b) -4./x-8/+12=0
c) (x^2-9).(x^2+1)=0
d) (x^2-8).(x^2+8)<0
e) (x^2-5).(x^2-20)<0
c) =>x mũ 2 -9<0 hoăc x mũ 2 +1 <0
Mà x mũ 2+1>0 => x mũ 2+1 ko thể <0
=>x mũ 2 -9< 0
=>x mũ 2 <9
=>x<3 hoặc x> -3
Mk làm nhầm bạn sửa dấu > và < thành dấu bằng là đc nhé sorry
1 Tìm x biết
a) -3.(x-4)+5.(x-1)=-7
b) -4./x-8/+12=0
c) (x^2-9).(x^2+1)=0
d) (x^2-8).(x^2+8)<0
e) (x^2-5).(x^2-20)<0
a) -3(x-4)+5(x-1)=-7
=>-3x+12+5x-5=-7
=>2x+7=-7
=>2x=-14=>x=-7
b) -4./x-8/+12=0
=>/x-8/=3
=>x-8=3 hoặc -3
(tự tính)
(X-5) mũ 0 = (x-5) mũ 8
(X+5).(x-4)=0
(X-1).(x-3)=0
|5-x|=7
\(\Rightarrow\left(x-5\right)^8=1\)
\(\Rightarrow x-5=1\)
\(x=1+5=6\)
\(\left(x+5\right)\cdot\left(x-4\right)=0\)\(\Rightarrow x+5=0\) Hoặc \(x-4=0\)
\(x=0-5=\left(-5\right)\) \(x=0+4=4\)
\(\left(x-1\right)\cdot\left(x-3\right)=0\)\(\Rightarrow x-1=0\) Hoặc \(x-3=0\)
\(x=0+1=1\) \(x=0+3=3\)
\(\left|5-x\right|=7\)\(\Rightarrow5-x=7\) Hoặc \(5-x=\left(-7\right)\)
\(x=5-7=\left(-2\right)\) \(x=5-\left(-7\right)=12\)