Số đèn trên trời có:

`14:40% = 35(cái-đèn)`

Số đèn trên trời có : 35 cái đèn KHỔNG MINH

                                 (vì 14 : 40% )

Hùng có số tấn gạo là:

    \(200xx3:(3+5)=75\) (tấn)

`3 : 5 = 3/5`

Tổng số phần bằng nhau :

`3 +5=8(phần)`

Số Hùng có số tấn gạo :

`200 : 8 xx 3= 75 (tấn)`

\(a,x \times 23-6 \times 23+x \times 69=230\)

\(x \times 23+x \times 69=230+6 \times 23\)

\(x \times (23+69)=368\)

\(x \times 92=368\)

\(x =368:92=4\)

~~~~~~~~~~~~~~~~~~~~~~~~~

`b,(x+1).(x+2)=72`

`x^2+2x+x+2=72`

`x^2+3x-70=0`

`x^2+10x-7x-70=0`

`x(x+10)-7(x+10)=0`

`(x+10)(x-7)=0`

`@TH1:x+10=0=>x=-10`

`@TH2:x-7=0=>x=7`

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

`c,(x+2).16x=160x`

`16x^2+32x-160x=0`

`16x^2-128x=0`

`16x(x-8)=0`

`@TH1:16x=0=>x=0`

`@TH2:x-8=0=>x=8`

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

`d,(x-5)(3x-18)=0`

`3x^2-18x-15x+90=0`

`3x^2-33x+90=0`

`x^2-11x+30=0`

`x^2-5x-6x+30=0`

`x(x-5)-6(x-5)=0`

`(x-5)(x-6)=0`

`@TH1:x-5=0=>x=5`

`@TH2:x-6=0=>x=6`

a, 23X - 6 x 23 + X x 69 = 230

23(X - 6 + 3X) = 230

      4X - 6 = 230 : 23

        4X - 6 = 10

     4X = 10 + 6

     4X = 16

X = 16 : 4

X = 4

b, (X+1)(X+2) = 72

    (X +1)(X+2) = 8x9

   X + 1 = 8

X = 8 - 1

X = 7

c, (X+2) x 16 x X = 160 x X

    ( X + 2 ) x 16 x X - 160 x X = 0

         16X ( X + 2 - 10) = 0

             \(\left[{}\begin{matrix}x=0\\x+2-10=0\end{matrix}\right.\) \(\Leftrightarrow\) \(\left[{}\begin{matrix}x=0\\x=8\end{matrix}\right.\)

x ϵ {0; 8}

d, (X - 5 )(3x -18) = 0

⇔ \(\left[{}\begin{matrix}x-5=0\\3x-18=0\end{matrix}\right.\) ⇔\(\left[{}\begin{matrix}x=5\\3x=18\end{matrix}\right.\)\(\Leftrightarrow\) \(\left[{}\begin{matrix}x=5\\x=6\end{matrix}\right.\)

x ϵ {5; 6}

4x16=>5x16

mong bn thông cảm ạ!!

`5 . 4^2 = 5 . 16 = 80`

\(a,18+x=384:8\)

\(18+x=48\)

\(x=48-18=30\)

~~~~~~~~~~~~~~~~~~~~~~

\(b.x \times 5=120:6\)

\(x \times 5=20\)

`x=20:5=4`

~~~~~~~~~~~~~~~~~~~~~~~~

\(c,5 \times (4+6 \times x)=2900\)

\(4+6 \times x=2900:5=580\)

\(6 \times x=580-4=576\)

\(x=576:6=96\)

~~~~~~~~~~~~~~~~~~~~~~~~~~~~

\(d,x \times 3,6+x \times 6,4=360:120\)

\(x \times (3,6+6,4)=3\)

\(x \times 10=3\)

\(x=3:10=\dfrac{3}{10}\)

`18 + x = 384 : 8`

`18 +x=48`

`x=48-18`

`x=30`

_________________

` x xx 5 = 120:6`

`x xx 5 = 20`

`x  =20 : 5`

`x=4`

________________

`5 xx ( 4 + 6 xx x ) = 2900`

`4 + 6 xx x = 2900 : 5`

`4 + 6 xx x = 580`

`6 xx x = 580 - 4`

`6 xx x = 576`

`x=576 : 6`

`x=96`

______________________

`x xx 3,6 x xx 6,4 =360:120`

`x xx 3,6 x xx 6,4 = 3`

`x xx ( 3,6 + 6,3) = 3`

`x xx 10  =3`

`x=3:10`

`x=3/10`

`x=0,3`

giải giúp mik với mn

`x : 5 xx 4 = 800`

`x : 20 = 800`

`x = 800 xx 20`

`x=16000`

___________________

`x : 5 : 4 = 800`

`x : 5/4 = 800`

`x  =800 xx 5/4`

`x=1000`

__________________

`x : 5 xx 4 = 800`

`x : 20 = 800`

`x = 800 xx 20`

`x=16000`

___________________

`x xx 5 : 4 = 800`

`x xx 5/4 = 800`

`x  =800 : 5/4`

`x = 800 xx 4/5`

`x=640`

`15x - 10x = 45-15`

`15x-10x=30`

`(15-10)x=30`

`5x=30`

`x=30:5`

`x=6`

15x - 10x = 45 - 15

15x - 10x = 30

5x = 30

x = 30 : 5

x = 6.

A = 1 + 2 + 3 + .......+ 10

A = (1 + 10 ) { (10-1) : 1 + 1} : 2

A = 11 x 10 : 2

A = 11 x 5

A = 55

  B = 2 + 2² + 2³ + .........+ 2¹⁰⁰

2B =       2² + 2² + .........+2¹⁰⁰ + 2¹⁰¹

2B - B = 2¹⁰¹ - 2

B =  2¹⁰¹ - 2