\(25+5x-4^3=251\)

\(\Rightarrow25+5x=315\)

\(\Rightarrow5x=315-25\)

\(\Rightarrow5x=290\)

\(\Rightarrow x=290:5=58\)

\(25+x.5-4^3=251\)

\(\Rightarrow25+x.5-64=251\)

\(\Rightarrow x.5=251+64-25\)

\(\Rightarrow x.5=290\)

\(\Rightarrow x=58\)

Vậy \(x=58\)

(15+x).5+x=225

<=>75+5x+x=225

<=>6x=150

<=>x=15

Vậy tập nghiệm S={15}

4/15 +1/2=23/30
51/9 - 2/3=5
3/4 x 15/26=45/104

7/3 : 5/14=98/15

4/15 + 1/2

= 8/30 + 15/30

= 23/30

51/9 - 2/3

= 51/9 - 6/9

= 45/9

= 5

3/4 × 15/26

= 45/104

7/3 : 5/14

= 7/3 × 14/5

= 98/15

thêm dấu ngoặc ở 1x=15/25+-19/25

x sai rùi nha

x pk là -6,25 nha

kết quả sai còn phần trên thì đúng

\(\dfrac{1}{x}=\dfrac{3}{5}+\dfrac{\left(-19\right)}{25}\)

\(\dfrac{1}{x}=-\dfrac{4}{25}\)

\(x=-\dfrac{\left(4\cdot1\right)}{25}\)

\(x=-\dfrac{4}{25}\)

Đây mới đúng nhé

a,\(x\div6=257-251\)

\(x\div6=6\)

\(x=1\)

b,\(x\times5=360-320\)

\(x\times5=40\)

\(x=8\)

a 

x : 6 = 257 - 251 

x : 6 = 6 

x = 6 x 6 

x = 36 

b 

X x 5 = 360 - 320 

X x 5 = 40 

X = 40 : 5 

X = 8 

a: \(\left(x+5\right)^2-\left(x-5\right)^2-2x+1=0\)

=>\(x^2+10x+25-\left(x^2-10x+25\right)-2x+1=0\)

=>\(x^2+8x+26-x^2+10x-25=0\)

=>18x+1=0

=>\(x=-\dfrac{1}{18}\)

b: \(\left(2x-7\right)^2-\left(x+3\right)^2=3x^2+6\)

=>\(4x^2-28x+49-\left(x^2+6x+9\right)-3x^2-6=0\)

=>\(x^2-28x+43-x^2-6x-9=0\)

=>34-34x=0

=>34x=34

=>x=1

c: \(\left(3x+2\right)^2-9\left(x-5\right)\left(x+5\right)=225-5x\)

=>\(9x^2+12x+4-9\left(x^2-25\right)-225+5x=0\)

=>\(9x^2+17x+4-225-9x^2+225=0\)

=>17x+4=0

=>x=-4/17

a,

\(\left(x-5\right)^2=225\)

\(\left(x-5\right)^2=15^2\)

\(\Rightarrow x-5=15\)

\(x=15+5\)

\(x=20\)

Vậy...

b.

\(\left(x-2\right)^5=32\)

\(\left(x-2\right)^5=2^5\)

\(\Rightarrow x-2=2\)

\(x=2+2\)

\(x=4\)

Vậy...

a,15

b,4

chúc bn học tốt^^