https://hoc24.vn/cau-hoi/a-5x-2x-62-50b-5x-x-150-2-3c-6x-x-511-59-31d-5x-3x-36-334-124x-2x-68-219-216.2785429565572

a: \(\Leftrightarrow7x=35\)

hay x=5

b: \(\Leftrightarrow6x=78\)

hay x=13

x^3/8 = y^3/64 = z^3/216 
=> (x/2)^3 = (y/4)^3 = (z/6)^3 
=> x/2 = y/4 = z/6 
=> x^2/4 = y^2/16 = z^2/36 = (x^2 + y^2 + z^2)/(4 + 16 + 36) = 14/56 = 1/4 (t.c dãy tỉ số bằng nhau) 
Suy ra : 
x^2 = 1 => x = 1 v x = -1 
y^2 = 4 => y = 2 v y = -2 
z^2 = 9 => z = 3 v z = -3

a: \(\Leftrightarrow6x=30\)

hay x=5

b: \(\Leftrightarrow6x=25+12-1=36\)

hay x=6

A x=5

B x = 6 (36)

a: \(\Leftrightarrow8x=108+12=120\)

hay x=15

b: \(\Leftrightarrow6x=60\)

hay x=10

a) 5x + 3x = 120
    x . (5+3)= 120
    x . 8       = 120
    x            = 120 : 8
    x            = 15

c) 7x - 2x = 40
    x .(7-2)= 40
    x . 5     = 40

    x          = 40 : 5
    x          = 8

2x²+2y²+2z²=1 hay (2x)²+(2y)²+(2z)²=1

\(\text{Ta có:}\)\(\frac{3x}{8}=\frac{3y}{64}=\frac{3z}{216}\)

\(\Rightarrow\frac{3}{8}x=\frac{3}{8}.\frac{y}{8}=\frac{3}{8}.\frac{z}{17}\)

\(\Rightarrow x=\frac{y}{8}=\frac{z}{27}\)

\(\text{Đặt:}\)\(x=\frac{y}{8}=\frac{z}{27}=k\)

\(\Rightarrow x=k\)

\(\frac{y}{8}=k\Rightarrow y=8k\)

\(\frac{z}{27}=k\Rightarrow z=27k\)

\(\text{Có:}\)\(2x^2-2y^2-z^2=1\)

\(\Rightarrow\left(2k\right)^2+2\left(8k^2\right)-27k^2=1\)

\(\Rightarrow k^2.\left(2+2.8^2-27^2\right)=1\)

\(\Rightarrow k^2.\left(-599\right)=1\)

\(\Rightarrow k^2=\frac{-1}{599}\left(\text{Vô lí}\right)\)

\(\Rightarrow x,y,z\text{ ko có gtrị}\)

Ta có: 3x/8= 3y/64= 3z/216

=> (3/8)x=(3/8)(y/8)=(3/8)(z/27)

=> x=y/8=z/27

=> x=k; y=8k; z=27k

Lại có: 2x^2 + 2y^2- z^2 = 1

2k^2 + 2(8k^2) - (27k)^2=1 

k^2(2+2*8^2-27^2)= 1

k^2*(-599)=1

k^2= 1/-599( vô lí)

Vậy x,y,z không có giá trị

ban dang xong tu tra loi thi dang lam cai j?

khôn thế,thế tớ cũng làm theo