Question

Решите срочно
7х=28
2у+31=4
2(12-3z)=5z-52
13-(3х+17)=4(-5х)+55

Answer 1

( 1 )

$7x=28\\\\x=28:7\\\\x=4$

Проверка:

$7*4=28\\\\28=28$

( 2 )

$2y+31=4\\\\2y=4-31\\\\2y=-27\\\\y=-27:2\\\\y=-13,5$

Проверка:

$2*(-13,5)+31=4\\\\-27+31=4\\\\4=4$

( 3 )

$2(12-3z)=5z-52\\\\24-6z=5z-52\\\\-6z-5z=-52-24\\\\-11z=-76\\\\z=-76:(-11)\\\\z=6\frac{10}{11}$

Проверка:

$2(12-3*6\frac{10}{11})=5*6\frac{10}{11}-52\\\\2(12-3*\frac{76}{11})=5*\frac{76}{11}-52\\\\2(12-\frac{228}{11})= \frac{380}{11}-52 \\\\2(\frac{132}{11}-\frac{228}{11})=\frac{380}{11}- \frac{572}{11}\\\\2*(-\frac{96}{11})=-\frac{192}{11} \\\\-\frac{192}{11}=-\frac{192}{11}$

( 4 )

$13-(3x+17)=4(-5x)+55\\\\13-3x-17=-20x+55\\\\-3x+20x=55-13+17\\\\17x=59\\\\x=59:17\\\\x=3\frac{8}{17}$

Проверка:

$13-(3*3\frac{8}{17}+17)=4(-5*3\frac{8}{17})+55\\\\13-(3*\frac{59}{17}+17)=4(-5*\frac{59}{17})+55\\\\13-( \frac{177}{17}+17)=4(- \frac{295}{17})+55\\\\13-(\frac{177}{17}+\frac{289}{17})= -\frac{1180}{17}+55 \\\\\frac{221}{17}-\frac{466}{17}=-\frac{1180}{17}+\frac{935}{17}\\\\-\frac{245}{17}=-\frac{245}{17}$