1 ) ( x - 15 ) : 2 = 10

x - 15 = 10 x 2

x - 15 = 20

x = 20 + 15

x = 35

2 ) 19 - 9 . ( x - 10 ) = 1

9 . ( x - 10 ) = 19 - 1

9 . ( x - 10 ) = 18

x - 10 = 18 : 9

x - 10 = 2

x = 10 + 2 

x = 12

21 . x + 21 . 10 = 2100

21 . ( x + 10 ) = 2100

x + 10 = 2100 : 21

x + 10 = 100

x = 100 - 10

x = 90

( x - 15 ) :2 = 10

 x - 15     = 10 : 2

x - 15        = 5

x               = 5 + 15

x                20

19 - 9 * ( x - 10 ) = 1

       9 * ( x - 10 ) = 19 -1

       9 *  ( x - 10 ) = 18

                x - 10= 18:9

                 x - 10 = 2

                 x         = 2 +10

                x          = 12

21 * x + 21 * 10 = 2100

21 * ( x + 10 )     = 2100

          x + 10      = 2100 : 21

          x + 10      =100

           x             = 100 - 10

            x             = 90

Cái ... =?

Nếu ... = ... thì đáp số là ...

B

b

a) x . x . x = 125

x³ =125

x³ = 5³

= > x = 5

b) ( x + 500 ) = 1000 - 200 . 2

x + 500 = 1000 - 400

x + 500 = 600

x = 600 - 500

x = 100

c) [( x + 10 ) . 100 ] = 500 + 500 . 10

( x + 10 ) . 100 = 500 + 5000

( x + 10 ) . 100 = 5500

x + 10 = 5500 : 100

x + 10 = 55

x = 55 - 10

x = 45

x + 500 = 500 + 10

x + 500 = 510

          x = 510 - 500

          x = 10

ai k mk mk k lại ^_^

= 10 chứ gì

x + 500 = 500 + 10

X + 500 = 510

       x = 510 - 500

A=(2+2^2+2^3+2^4)+2^4(2+2^2+2^3+2^4)+...+2^96(2+2^2+2^3+2^4)

=30(1+2^4+...+2^96) chia hết cho 10

x + 500 = 500 + 10

x + 500 = 510

         x = 510 - 500

         x = 10

x + 500 = 500 + 10

x + 500 = 510

          x = 510 - 500

          x = 10

ai tk mk mk tk lại

X+500=500+10

X+500=510

X=510-500

X=10

a)-7x+7=21                                          

-7x=21-7

-7x=16

x=16:-7

x=-16/7

\(a,-7x+7=21\)

\(\Rightarrow-7x=21-7=14\)

\(\Rightarrow x=-2\)

\(b,9x+11=20x+66\)

\(\Rightarrow9x-20x=66-11=55\)

\(\Rightarrow-11x=55\)

\(\Rightarrow x=-5\)

\(c,3^3.x+4^2=5^2.x-2.\left(2017\right)^0\)

\(27x+16=25x-2\)

\(\Rightarrow16+2=25x-27x=-2x\)

\(\Rightarrow-2x=18\)

\(\Rightarrow x=-9\)

\(d,\left(2+3+...+20\right)x=2100\)

\(\Rightarrow\frac{\left(20+2\right)\left[\left(20-2\right):1+1\right]}{2}x=2100\)

\(11.19.x=2100\)

\(\Rightarrow x\simeq10\)

\(e,5\left(\left|x\right|-14\right)=10\)

\(\Rightarrow\left|x\right|-14=10:5=2\)

\(\Rightarrow\left|x\right|=16\)

\(\Rightarrow x=\orbr{\begin{cases}16\\-16\end{cases}}\)

a)1700

b)2000

a, 500+500+500+(100 x 2)

=500 x 3+ 100x2

=1500+200

=1700

b, 700+300+(100 x 10)=700+300+1000=1000+1000=2000

k minh nha

a) = 1700

b) =2000