Tim x,y,z biet:
a, x/2=y/3; y/5=z/7 va x+y+z=138
b, 10x=15y=21z va 3x-7y+5z=30
cac ban oi giup minh voi
1.tim a,b thuoc Z,biet:a.(2b-3)=-6
2.cho x,y thuoc Z thoa man x mu 2 +y mu 2 chia het cho 3.chung to x va y chia het cho 3.
Tim cac so nguyen x,y biet:a)*x2 -3*x+1 chia het cho x+2 b)x2-xy = 5x-4y-9 c) (x2-8)*(x2-15)<0 d) (x+1)2+(y+1)2+(x-y)2=2 e) (x2-4)x2>0 ai lam truoc minh tick,mai minh di hoc rui,lam giup minh di pls Thank ban truoc ne ;(
tim x biet:a)/x+1/+/3x-1/+/x-1/=3
b)/x-2/+/x-7/=4
|x+1|+|3x-1|+|x-1|=3
=} vs cả trong dấu giá trị tuyệt đối >0 thì=}
x+1+3x-1+x-1=3{=}5x=4{=}x=4/5
=}vs cả trong giá trị tuyệt đối <0 thì=}
x+1+3x-1+x-1=-3{=}5x=-4{=}x=-4/5
Cau 3 (2 diem). Tim so tu nhien x, biet:
a. 123 - x =38
b. (x+15) - 7 =33
c. 3x+3 - 13=230
`123-x=38`
`=> x= 123-38`
`=>x=85`
Vậy `x=85`
__
`(x+15) -7=33`
`=>x+15=33+7`
`=>x+16= 40`
`=>x=40-16`
`=>x=24`
Vậy `x=24`
__
`3^(x+3) -13=230`
`=> 3^(x+3) = 230+13`
`=>3^(x+3)=243`
`=> 3^(x+3)=3^5`
`=> x+3=5`
`=>x=5-3`
`=>x=2`
Vậy `x=2`
tim x biet:a.2x^2-1=17/8;b.(2x-0,05)(x+3)>0;c.(7-x)(x+19)>0
tim x,y,z biet y+z+1=x+z+2/y=x+y-3/2=1/x+y+z
tim x; y; z biết y+z+1/x=x+z+2/y=x+y-3/z=1/x+y+z
tim x nguyen biet:
a 8.(x mu 2 +3).(5-x)
b)(2x + 1)mu 2=25
c) (1-3x)mu3 =64
d)(4-x)mu3 =-27
e) xmu2 -5x =0
b: \(\left(2x+1\right)^2=25\)
=>\(\left[{}\begin{matrix}2x+1=5\\2x+1=-5\end{matrix}\right.\)
=>\(\left[{}\begin{matrix}2x=4\\2x=-6\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=2\\x=-3\end{matrix}\right.\)
c: \(\left(1-3x\right)^3=64\)
=>\(\left(1-3x\right)^3=4^3\)
=>1-3x=4
=>3x=1-4=-3
=>x=-3/3=-1
d: \(\left(4-x\right)^3=-27\)
=>\(\left(4-x\right)^3=\left(-3\right)^3\)
=>4-x=-3
=>x=4+3=7
e: \(x^2-5x=0\)
=>\(x\left(x-5\right)=0\)
=>\(\left[{}\begin{matrix}x=0\\x-5=0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=0\\x=5\end{matrix}\right.\)
tim x,y,z (cau a ) , tim x , y (cau b )
a, x : y : z = 3 : 4 : 5 va 5z2 - 3x2 - 2y2 = 594
b, z + y = x : y = 3.(x - y )
a) Đặt: x3=y4=z5=Kx3=y4=z5=K
=> x= 3K ; y = 4K ; z = 5K
Theo đề bài ta có: 5z2−3x2−2y2=5945z2−3x2−2y2=594
Hay: 5×(5K)2−3×(3K)2−2×(4K)2=5945×(5K)2−3×(3K)2−2×(4K)2=594
5 * 25K2 - 3* 9K2 - 2* 16K2 = 594
125K2 - 27K2 - 32K2 = 594
66K2 = 594
=> K2 = 594 : 66 = 9
=> K= căn của 9 = ±3±3
Với K = 3
=> x = 3 * 3 = 9
y = 4 * 3 = 12
z = 5 * 3 = 15
Với K = - 3
=> x = 3 * (- 3) = - 9
y = 4 * (- 3) = - 12
z = 5 * (- 3)= - 15
Vậy x = ±9±9 ; y = ±12±12 ; z = ±15
tim ba số x,y,z biết :x+y=2,y+z=3,z+x=-5 x= y= z