Найди корни уравнений и сделай проверку: а) 26+х3=50 д) 99-540: (а-27)=155 б) 480: y-19=41 е) 80b-390+430=1600: 2 в)160/t+18=252 ж) 6 целых 1/7 - (с+2 целых 4/7) =2 целых 5/7 г) k/7-34=78: 3 з) 3 целых 5/16+(d- 1 целых 7/16)= 9 целых 1/16

Ответы

89508122482 01.10.2020 20:53

а) 26+x·3=50

3·x=50–26

3·x=24

х=24:3

х=8

Проверка:

26+8·3=26+24=50 верно!

б) 480:y–19=41

480:y=41+19

480:y=60

480=60·y

у=480:60

у=8

Проверка:

480:8–19=60–19=41 верно!

в) 160:t+18=25·2

160:t+18=50

160:t=50–18

160:t=32

160=32·t

t=160:32

t=5

Проверка:

160:5+18=25·2

32+18=50

50=50 верно!

г) k:7–34=78:3

k:7–34=26

k:7=26+34

k:7=60

k=60·7

k=420

Проверка:

420:7-34=78:3

60–34=26

26=26 верно!

д) 9·9–540:(а-27)=15·5

81–540:(a–27)=75

81–75=540:(a–27)

6=540:(a–27)

6·(a–27)=540

a–27=540:6

a–27=90

a=90+27

a=117

Проверка:

9·9–540:(117–27)=15·5

81–540:90=75

81–6=75

75=75 верно!

е) 80·b–3·90+430=1600:2

80·b–270=800–430

80·b=370+270

80·b=640

b=640:80

b=8

Проверка:

80·8–3·90+430=1600:2

640–270+430=800

370+430=800

800=800 верно!

ж) 6 1/7 – (с+2 4/7) = 2 5/7

$\displaystyle 6\frac{1}{7}-(c+2\frac{4}{7})=2\frac{5}{7}\\\\6\frac{1}{7}-2\frac{5}{7}=c+2\frac{4}{7}\\\\3\frac{8}{7}-\frac{5}{7}=c+2\frac{4}{7}\\\\c+2\frac{4}{7}=3\frac{3}{7}\\\\c=3\frac{3}{7}-2\frac{4}{7}\\\\c=\frac{10}{7}-\frac{4}{7}\\\\c=\frac{6}{7}$

Проверка:

$\displaystyle 6\frac{1}{7}-(\frac{6}{7}+2\frac{4}{7})=2\frac{5}{7}\\\\6\frac{1}{7}-2\frac{10}{7}=2\frac{5}{7}\\\\6\frac{1}{7}-3\frac{3}{7}=2\frac{5}{7}\\\\2\frac{8}{7}-\frac{3}{7}=2\frac{5}{7}\\\\2\frac{5}{7}=2\frac{5}{7}$

верно!

з) 3 5/16+(d – 1 7/16)= 9 1/16

$\displaystyle 3\frac{5}{16}+(d-1\frac{7}{16})=9\frac{1}{16}\\\\d-1\frac{7}{16}=9\frac{1}{16}-3\frac{5}{16}\\\\d-1\frac{7}{16}=5\frac{17}{16}-\frac{5}{16}\\\\d-1\frac{7}{16}=5\frac{12}{16}\\\\d=5\frac{12}{16}+1\frac{7}{16}\\\\d=6\frac{19}{16}=7\frac{3}{16}$

Проверка:

$\displaystyle 3\frac{5}{16}+(7\frac{3}{16}-1\frac{7}{16})=9\frac{1}{16}\\\\3\frac{5}{16}+(5\frac{19}{16}-\frac{7}{16})=9\frac{1}{16}\\\\3\frac{5}{16}+5\frac{12}{16}=9\frac{1}{16}\\\\8\frac{17}{16}=9\frac{1}{16}\\\\9\frac{1}{16}=9\frac{1}{16}$