a+b=252
a=b+42

a-b=28
a+b=490

helppppp va rogggg dau coroanaaa


Răspuns :

1)
a+b=252
a=b+42
b+42+b=252
2b+42=252
2b=252-42
2b=210
b=210:2
b=105
a=105+42
a=147

2)
a-b=28 => a=b+28
a+b=490
b+28+b=490
2b+28=490
2b=490-28
2b=462
b=462:2
b=231
a=231+28
a=259
b+42+b=252
2b=252-42
2b=210
b=105
a=105+42
a=147

(a-b)(a+b) =28×490=13720