112-45+5x=87
45+5x=112-87
5x=25-45
x=-25:5
x=_5

12 : 35 = \(\frac{12}{35}\)

112 : 63 = \(\frac{112}{63}\)

41 : 100 = \(\frac{41}{100}\)

217 : 100 = \(\frac{217}{100}\)

11 : 45 = \(\frac{11}{45}\)

416 : 87 = \(\frac{416}{87}\)

12 : 35 = 12/35

112 : 63 = 112/63

217: 100 = 217/100

11 : 45 = 11/45

416: 87 = 416/87

tự làm đi có làm thì mới có ăn chứ

\(e,112-45+5x=87\)

\(67+5x=87\)

\(5x=20\)

\(x=4\)

\(f,6^2+64:\left(x-1\right)=52\)

\(36+64:\left(x+1\right)=52\)

\(64:\left(x+1\right)=16\)

\(x+1=4\)

\(x=3\)

\(g,\left(55-x\right)\left(2x-44\right)=0\)

\(\Rightarrow\hept{\begin{cases}55-x=0\\2x-44=0\end{cases}}\)

\(\Rightarrow\hept{\begin{cases}x=55\\x=22\end{cases}}\)

Vậy ....

\(h,x^2+4=13\)

\(x^2=9\)

\(x^2=\pm3^2\)

\(\Rightarrow x=\pm3\)

\(i,2\left(x+1\right)^3=16\)

\(\left(x+1\right)^3=8\)

\(\left(x+1\right)^3=2^3\)

\(\Rightarrow x+1=2\)

\(x=1\)

\(g,150-5\left(x-2\right)^2=25\)

\(5\left(x-2\right)^2=125\)

\(\left(x-2\right)^2=25\)

\(\left(x-2\right)^2=\pm5^2\)

\(\Rightarrow\hept{\begin{cases}x-2=5\\x-2=\left(-5\right)\end{cases}\Rightarrow\hept{\begin{cases}x=7\\x=\left(-3\right)\end{cases}}}\)

Vậy .... 

a, 5x = 201 - 6 = 195

     x  = 195 : 5 = 39

b, 135 - 2x = 87

            2x = 135 - 87 = 48

             x  = 48 : 2 = 24

c, 45 - ( x - 17 ) : 3 = 38

          ( x - 17 ) : 3 = 45 - 38 =7

              x - 17      = 7 . 3 = 21

                 x         = 21 + 17  =  38

\(5^x+5^{x+1}+5^{x+2}+5^{x+3}=1+2+3+...+87+88-4^2\)

=>\(5^x+5^x\cdot5+5^x\cdot25+5^x\cdot125=88\cdot\dfrac{\left(88+1\right)}{2}-16\)

=>\(156\cdot5^x=44\cdot89-16=3900\)

=>\(5^x=\dfrac{3900}{156}=25\)

=>x=2

=87.(-17+(-83)=87.(-100)=-8700

=-45.(1+432-432)=-45.1=-45

a, =87[-17+(-83)]

=87.(-100)

=-8700

b, =(-45)+-(45).432-432.(-45)

(-45)+(-45)(432-432)

=(-45)+0

=-45

tính hợp lý
87 x (- 17) + (- 83) x 87

= 87.[-17+(-83)]

=87.(-100)

=-8700
(- 45) x (1 + 432) - 432 x (- 45)

=-45.433-432.(-45)

=-45.(433-432)

=-45.1

=-45

Lời giải:

$5^x+5^{x+1}+5^{x+2}+5^{x+3}=1+2+3+...+87+88-4^2$

$5^x(1+5+5^2+5^3)=88.89:2-16$

$5^x.156=3900$

$5^x=3900:156=25=5^2$

$\Rightarrow x=2$

( 13 * 78 + 13 * 22 ) + ( 87 * 55 + 87 * 45 )

= 13 * ( 78 + 22 ) + 87 * ( 55 + 45 )

= 13 *    100   +    87 *   100

= 1300   + 8700

=      10 000

12 chia 35 bằng 12/35               112 chia 63 bằng 112/63                41 chia 100 bằng 41/100

 217 chia 100 bằng 217/100               11 chia 45 bằng 11/45               416 chia 87 bằng 416/87

12 chia 35 bằng \(\frac{12}{35}\)

112 chia 63 bằng \(\frac{16}{9}\)

41 chia 100 bằng\(\frac{41}{100}\)

217 chia 100 bằng\(\frac{217}{100}\)

416 chia 87 bằng\(\frac{416}{87}\)

11 chia 45 bằng\(\frac{11}{45}\)

12:35=12/35                                             112:63=16/9

41:100=41/100                                         217:100=217/100

11:45=11/45                                               416:87=416/87