Question

quanto vale x? a) {2/7,4/5}={x,2/7} b) [2/10,x/4]={1/5,6/8]

Answer 1

Resposta:

a

(2/7)/(4/5)  =  x/(2/7)

multiplica em cruz

4/5 * x   =  2/7 * 2/7

notas

4/5 * x/1 =  4x/5 >>>

2/7  * 2/7   = 4/49 >>>

reescrevendo

4x/5  = 4/49

multiplica em cruz

4x * 49   = 5 * 4

196x =  20

x = 20/196  = por 4 = 5/49 >>>> resposta

b

( 2/10) / ( x/4)  =  ( 1/5) / ( 6/8)

multiplica em cruz

x/4  * 1/5   = 2/10 *  6/8

1x/20  = 12/80

Notas

x/4  * 1/5  =  ( 1 * x) / ( 4 * 5 )  = x/20

2/10 * 6/8   = 12/80

reescrevendo

x/20  =12/80

multiplica em cruz

80 * x = 20 * 12

80x = 240

x = 240/80  = 3 >>>>resposta