282 là đúng mình làm trên Violympic rồi

282 la dung day

282 ban a

282 nhe ban

làm thế nào mà ra 282?

= 6

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

\(\Rightarrow\left[{}\begin{matrix}x-2=0\\x+4=0\end{matrix}\right.\)

\(\Rightarrow\left[{}\begin{matrix}x=2\\x=-4\end{matrix}\right.\)

2) \(\left(x-2\right)\left(x+15\right)=0\)

\(\Rightarrow\left[{}\begin{matrix}x-2=0\\x+15=0\end{matrix}\right.\)

\(\Rightarrow\left[{}\begin{matrix}x=2\\x=-15\end{matrix}\right.\)

3) \(\left(7-x\right)\left(x+19\right)=0\)

\(\Rightarrow\left[{}\begin{matrix}7-x=0\\x+19=0\end{matrix}\right.\)

\(\Rightarrow\left[{}\begin{matrix}x=7\\x=-19\end{matrix}\right.\)

4) \(-5< x< 1\)

\(\Rightarrow x\in\left\{-1;-3;-2;-1;0\right\}\)

5) \(\left(x-3\right)\left(x-5\right)< 0\)

\(\Rightarrow\left[{}\begin{matrix}x-3>0\\x-5< 0\end{matrix}\right.\)

\(\Rightarrow\left[{}\begin{matrix}x>3\\x< 5\end{matrix}\right.\)

\(\Rightarrow3< x< 5\)

6) \(2x^2-3=29\)

\(\Rightarrow2x^2=29+3\)

\(\Rightarrow2x^2=32\)

\(\Rightarrow x^2=\dfrac{32}{2}\)

\(\Rightarrow x^2=16\)

\(\Rightarrow x^2=4^2\)

\(\Rightarrow\left[{}\begin{matrix}x=4\\x=-4\end{matrix}\right.\)

7) \(-6x-\left(-7\right)=25\)

\(\Rightarrow-6x+7=25\)

\(\Rightarrow-6x=25-7\)

\(\Rightarrow-6x=18\)

\(\Rightarrow x=\dfrac{18}{-6}\)

\(\Rightarrow x=-3\)

8) \(46-\left(x-11\right)=-48\)

\(\Rightarrow x-11=48+46\)

\(\Rightarrow x-11=94\)

\(\Rightarrow x=94+11\)

\(\Rightarrow x=105\)

1: (x-2)(x+4)=0

=>x-2=0 hoặc x+4=0

=>x=2 hoặc x=-4

2: (x-2)(x+15)=0

=>x-2=0 hoặc x+15=0

=>x=2 hoặc x=-15

3: (7-x)(x+19)=0

=>7-x=0 hoặc x+19=0

=>x=7 hoặc x=-19

4: -5<x<1

=>\(x\in\left\{-4;-3;-2;-1;0\right\}\)

5: (x-3)(x-5)<0

=>x-3>0 và x-5<0

=>3<x<5

6: 2x^2-3=29

=>2x^2=32

=>x^2=16

=>x=4 hoặc x=-4

7: -6x-(-7)=25

=>-6x=25-7=18

=>x=-3

8: 46-(x-11)=-48

=>x-11=46+48=94

=>x=94+11=105

7,x²-2xy+y²+3x-3y=(x-y)²+3(x-y)=(x-y)(x-y+3)

8,x⁴+4=(x⁴+4x²+4)-4x²=(x²+2)²-(2x)²=(x²-2x+2)(x²+2x+2)

9,4x(x+1)²-5x²(x+1)-4.(x+1)=(x+1)\(\left[4x\left(x+1\right)-5x^2-4\right]\)=(x+1)(4x²+4x-5x²-4)=(x+1)(-x²+4x-4)=-(x+1)(x-2)²

7: \(x^2-2xy+y^2+3x-3y\)

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

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

8: \(x^4+4\)

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

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

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

9: \(4x\left(x+1\right)^2-5x^2\left(x+1\right)-4\left(x+1\right)\)

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

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

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

10: \(\left(1+2x\right)\left(1-2x\right)-\left(x+2\right)\left(x-2\right)\)

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

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

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

a) (x-2).(x+4)=0

<=> hoặc x-2=0 hoặc x+4=0

<=> hoặc x=2 hoặc x=-4

               Vậy x \(\in\){-4;2}

b) 2x²-3=29

=> 2x²=32

=> x²=16

<=> x=4

c) 45-(x-11)=-48

         x-11 = 45-(-48)

         x-11 = 45+48

         x-11 = 93

         x = 93+11

         x = 104 

=88.57596425 nha bn.