m(a-z)-n(a-z)+2(a-z)=(m-n+2)(a-z)
2х+3y=23 (3)
4y-3x=8 (2)
Складываем 17y=85 y=5
2x+15=23
x=4
100^k/(2*(2k-1))*(5^(2k-2))=
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