<=> 1/2 * x - 2/3 * x = 5/12

<=> x *(1/2 - 2/3) = 5/12

<=> x * (-1/6) = 5/12

<=> x = 5/12 : (-1/6)

<=> x = -5/2 (tm)

Phân tích 3(x-3)(x+3+4)+x^2 - 8x + 16 +48 
3(x -3)[(x +3) + 4] + x^2 - 8x +64 
3(x -3)(x +3) + 12 (x-3) + x^2 - 8x +64 
3(x^2 - 9) + 12x - 36 + x^2 - 8x +64 
3X^2 -27 +4x +28 + x^2 
4x^2 +4x +1 
(2x+1)^2 

Thay x = 0,5 vào được (2.0,5 + 1)^2 = 4

Đáp số: 19,5

a) x = 40

b) x = 18

c) x = KHÔNG NHỚ NỮA

\(a,\frac{3}{35}-\left[\frac{3}{5}+x\right]=\frac{2}{7}\)

\(\Rightarrow\frac{3}{5}+x=\frac{3}{35}-\frac{2}{7}\)

\(\Rightarrow\frac{3}{5}+x=\frac{3}{35}-\frac{2\cdot5}{35}\)

\(\Rightarrow\frac{3}{5}+x=\frac{3}{35}-\frac{10}{35}=\frac{-7}{35}\)

\(\Rightarrow x=\frac{-7}{35}-\frac{3}{5}=\frac{-7}{35}-\frac{3\cdot7}{35}=\frac{-7}{35}-\frac{21}{35}=\frac{-28}{35}=\frac{-4}{5}\)

\(b,\frac{5}{6}+\frac{1}{6}:x=\frac{3}{4}\)

\(\Rightarrow\frac{1}{6}:x=\frac{3}{4}-\frac{5}{6}\)

\(\Rightarrow\frac{1}{6}:x=\frac{18}{24}-\frac{20}{24}\)

\(\Rightarrow\frac{1}{6}:x=\frac{-2}{24}\)

\(\Rightarrow x=\frac{1}{6}:\frac{-2}{24}=\frac{1}{6}:\frac{-1}{12}=\frac{12}{-6}=\frac{-12}{6}=-2\)

\(c,\left|x-3\frac{4}{7}\right|=-0,5\)

Vì \(\left|x-3\frac{4}{7}\right|\ge0\)mà \(-0,5< 0\)nên \(x\in\varnothing\)

Vậy không có giá trị x thỏa mãn

a)  3/35-(3/5+x)=2/7

<=> 3/5+x=3/35-2/7

<=> 3/5+x=3/35-10/35

<=> 3/5+x=-7/35

<=> 3/5+x=-1/5

<=> x=-1/5-3/5

<=> x=-4/5

Vậy x=-4/5

a) Ta có :

\(\frac{7}{12}< \frac{x}{24}< \frac{2}{3}\)

\(\Rightarrow\frac{14}{24}< \frac{x}{24}< \frac{16}{24}\)

\(\Rightarrow14< x< 16\)

\(\Rightarrow x=15\)

Vậy x = 15

b) \(\left(x+1\right)+\left(x+4\right)+\left(x+7\right)+...+\left(x+28\right)=195\)

\(\Rightarrow\left(x+x+x+...+x\right)+\left(1+4+7+...+28\right)=195\)

\(\Rightarrow10x+145=195\)

\(\Rightarrow10x=195-145\)

\(\Rightarrow10x=50\)

\(\Rightarrow x=50:10\)

\(\Rightarrow x=5\)

Vậy x = 5

c) \(\left(x+0,5\right)+\left(x+1,5\right)+\left(x+2,5\right)=33\)

\(\Rightarrow\left(x+x+x\right)+\left(0,5+1,5+2,5\right)=33\)

\(\Rightarrow3x+4,5=33\)

\(\Rightarrow3x=33-4,5\)

\(\Rightarrow3x=28,5\)

\(\Rightarrow x=28,5:3\)

\(\Rightarrow x=9,5\)

Vậy x = 9,5

_Chúc bạn học tốt_

a, \(\frac{7}{12}\)\(< \)\(\frac{x}{24}\)\(< \)\(\frac{2}{3}\)

\(\frac{14}{24}\)\(< \)\(\frac{x}{24}\)\(< \)\(\frac{16}{24}\)

Số lớn hơn 14 và nỏ hơn 16 là : 15

\(\Rightarrow\)Vậy \(x\)= 15

a, x=15 (như Jin Ji Hee làm)

b, (x+0,5)+(x+4)+(x+7)+....+(x+28)=195

=>x+0,5+x+4+x+7+....+x+28=195

=>(x+x+x+...+x)+(0,5+4+7+...+28)=195

=>10.x+144,5=195

=>10.x = 50,5 => x=50,5: 10=5,05

Vậy x= 5,05

c, (x+0,5)+(x+1,5)+(x+2,25)=33

=> x+0,5+x+1,5+x+2,25=33

=> (x+x+x)+(0,5+1,5+2,25)=33

=>3x+4,25=33=>3x= 28.75=> x=\(\frac{115}{12}\)

Vậy x=\(\frac{115}{12}\)

chúc bạn hk tốt!!(nhớ k cho mình nha!!@@)

3(x-3)(x+7)+(x-4)²+48

=3(x²+7x-3x-21)+(x²-8x+16)+48

=3x²+21x-9x-63+x²-8x+16+48

=3x²+x²+21x-9x-8x-63+16+48

=4x²+4x+64

=4(x²+x+16)

Ta thay x=0,5 vào đa thức :

=4(0,5²+0,5+16)

=4.16,75

=67