x + 1 + x + 3 +x + 5 + x + 7 + x + 9 = 750

  ( x + x + x + x + x ) + ( 1 + 3 + 5 + + 7 + 9 ) = 750

     x x 5 + 25 = 750

     x x 5 = 750 - 25

     x x  5 = 725

           x = 725 :5

           x = 145

x=750:(1+3+5+7+9)

x=750:25

x=30

x+1+x+3+x+5+...+x+9 

= ( x+x+x+x)+ (1+3+5+9)

=x*5+25=750

  x*5=750-25

  x*5=725

     x= 725:5

     x=145

\(5^X+5^{X+1}=750\\ 5^X\cdot\left(1+5\right)=750\\ 5^X\cdot6=750\\ 5^X=125\\X=3 \)

trả lời gấp nha

Giải 

( x + 1 ) + ( x + 3 ) + ( x + 5 ) + ( x + 7 ) + ( x + 9 ) = 750

x x ( 1 + 3 + 5 + 7 + 9 ) = 750

x x 25 = 750 

x        = 750 : 25

x        = 30

Đúng nha

Bạn sai rồi

(x + 1) + (x + 3) + (x + 5) + (x + 7) + (x + 9) = 750

                             5x + (1 + 3 + 5 + 7 + 9) = 750

                                                    5x + 25 = 750

                                                            5x = 750 - 25

                                                            5x= 625

                                                             x = 625 : 5 

                                                             x = 125

                                                         Vậy x = 125

\(5^x+5^{x-1}=750\)

\(\Rightarrow5^x+5^x.\frac{1}{5}=750\)

\(\Rightarrow5^x.\left(1+\frac{1}{5}\right)=750\)

\(\Rightarrow5^x.\frac{6}{5}=750\)

\(\Rightarrow5^x=750:\frac{6}{5}\)

\(\Rightarrow5^x=625\)

\(\Rightarrow5^x=5^4\)

\(\Rightarrow x=4\)

Vậy \(x=4\)

Ta có : 5^x + 5^{x - 1} = 750

\(\Rightarrow\) 5^x + 5^{x - 1} = 625 + 125

\(\Rightarrow\) 5^x + 5^{x - 1} = 5⁴ + 5³

\(\Rightarrow\) x = 4

Vậy x = 4

\(5^x+5^{x-1}=750\)

\(\Rightarrow\)\(5^x+5^x.\dfrac{1}{5}=750\)

\(\Rightarrow\)\(5^x.\left(1+\dfrac{1}{5}\right)=750\)

\(\Rightarrow\)\(5^x.\dfrac{6}{5}=750\)

\(\Rightarrow\)\(5^x=750:\dfrac{6}{5}=625\)

\(\Rightarrow\)\(5^x=5^4\)

Vậy, x = 4

1 

\(\left(x-2\right):2.3=6\)

\(\Leftrightarrow\left(x-2\right):2=2\)

\(\Leftrightarrow\left(x-2\right)=4\)

\(\Leftrightarrow x=4+2=6\)

c) ta có

\(\left[\left(2x+1\right)+1\right]m:2=625\)

\(\Leftrightarrow\left[\left(2x+1\right)+1\right]\left\{\left[\left(2x+1\right)-1\right]:2+1\right\}=1250\)

\(\Leftrightarrow\left(2x+1\right)^2+1-1:2+1=1250\)

\(\Leftrightarrow\left(2x+1\right)^2+1-2+1=1250\)

\(\Leftrightarrow\left(2x+1\right)^2+1-2=1249\)

\(\Leftrightarrow\left(2x+1\right)^2+1=1251\)

\(\Leftrightarrow\left(2x+1\right)^2=1250\)

...

2

\(\left(x-\frac{1}{2}\right).\frac{5}{3}=\frac{7}{4}-\frac{1}{2}\)

\(\Leftrightarrow\left(x-\frac{1}{2}\right).\frac{5}{3}=\frac{5}{4}\)

\(\Leftrightarrow\left(x-\frac{1}{2}\right)=\frac{5}{4}:\frac{5}{3}\)

\(\Leftrightarrow\left(x-\frac{1}{2}\right)=\frac{5}{4}.\frac{3}{5}\)

\(\Leftrightarrow x-\frac{1}{2}=\frac{3}{4}\)

\(\Leftrightarrow x=\frac{3}{4}+\frac{1}{2}=\frac{5}{4}\)

Có \(5^x+5^{x+1}=750\)

=> \(5^x\left(1+5\right)=750\)

=> \(5^x=\frac{750}{6}=125\)

=> \(x=3\) 

Hok tốt nhen ^_^

\(x=3\)

học tốt

   a  25 + 8 + 12 + 25 = 70            b  87 + [ - 750   ] + 2018 - 13 + 750 = 2842             c [ 45 + 12 - 13 ]  -  [ 45 - 13 + 12 ]  =  90                minh tinh gom bn ah

rk đúng hay sai đây

Lời giải:

a) 

$1+3+5+...+(2x-1)=750$

$\frac{(2x-1+1)x}{2}=750$

$x^2=750$

$x=\sqrt{750}$ (vô lý?!!)

b) 

$1+5+9+13+...+x=501501$

$\frac{1}{2}(\frac{x-1}{4}+1)(x+1)=501501$

$(x+1)(x+3)=4012008$$x(x+4)=4012005=2001.2005$

$\Rightarrow x=2001$

\(5^{x+2}+5^{x+3}=750\)

\(5^x.5^2+5^x.5^3=750\)

\(5^x.25+5^x\cdot125=750\)

\(5^x.\left(25+125\right)=750\)

\(5^x.150=750\)

\(5^x=750:150\)

\(5^x=5\)

\(5^x=5^1\)

\(\Rightarrow x=1\)