tim x thuoc n biet ;
g/121 :11-(4 nhan x cong 5) chia 3 =4
h/2x cong 2x+1 = 96
k/34 nhan x +4 =81 x+3
j/(x -5)7=(x-5)9 chu y x nho hon hoac bang 5
l/x2015 =x2016
tim x thuoc n biet x^2016=x^5
\(x^{2016}=x^5\)
=>\(x^{2016}-x^5=0\)
=>\(x^5\left(x^{2011}-1\right)=0\)
=>x5=0 hoặc x2011-1=0
=>x=0 hoặc x=1
x=0 hoặc x=1
Vì: 12016=1
15=1
02016=0
05=0
tim x thuoc N, biet [x-1] [x+3]=6
\(\left(x-1\right)\left(x+3\right)=6\)
\(\Rightarrow6⋮\left(x-1\right),\left(x+3\right)\)
\(\Rightarrow\left(x-1\right),\left(x+3\right)\inƯ\left(6\right)\)
\(\RightarrowƯ\left(6\right)=\left\{1;2;3;6\right\}\)
Ta có bảng :
x - 1 | 1 | 2 |
x + 3 | 6 | 3 |
x | 2 | 3 |
x | 3 | 0 |
tim x,y thuoc N biet (x-6).(2y+3)=8
Tim x;y thuoc N biet (x-1)(2y+3)=26
\(\left(x-1\right)\left(2y+3\right)=1\cdot26=26\cdot1=2\cdot13=13\cdot2\)
Ta co bang sau:
x-1 | 1 | 26 | 2 | 13 | ||||
2y+3 | 26 | 1 | 13 | 2 | ||||
x | 2 | 27 | 3 | 14 | ||||
y | 11.5 (loai) | -1(loai) | 5 | -0.5(loai) |
tim x thuoc N biet 5 chia het cho x+1
tim x thuoc N biet 3n - 5 chia het cho n+1
tim x thuoc N biet :
(x+2).(2x+1)=24
tim x thuoc N biet 16 chia het cho (x-2)
16 chia hết cho (x-2)
=> \(\left(x-2\right)\inƯ\left(16\right)=\left\{1;2;4;8;16\right\}\)
=> \(x\in\left\{3;4;6;10;18\right\}\).
Nếu đã học số nguyên:
=> \(\left(x-2\right)\inƯ\left(16\right)=\left\{-16;-8;-4;-2;-1;1;2;4;8;16\right\}\)
=> \(x\in\left\{-14;-6;-2;0;1;3;4;6;10;18\right\}\)
16 chia het cho (x-2)=>x\(\in\)Ư(16)
Ư(16)\(\in\){1;2;4;8;16}
ta được
x-2=1 =>x=3
x-2=2 =>x=4
x-2=4 =>x=6
x-2=8 =>x=10
x-2=16 =>x=18
tim x,y thuoc N, biet x.y+2.x+y-13=0
\(\left(y+2\right)x+\left(y+2\right)=15\Leftrightarrow\left(y+2\right)\left(x+1\right)=15\)
x+1 | 1 | 3 | 5 |
y+2 | 15 | 5 | 3 |
x | 0 | 2 | 4 |
y | 13 | 3 | 1 |
tim x ,y thuoc N biet x.y + 2.x +y-13=0