Ответ: у<(x+3)²-4
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Умножим первое уравнение на (-2):
-8х+2у=-42
3х-2у=17
Складываем
-5х=-25
х=5
у=4х-21=4·5-21=20-21=-1
О т в е т. (5;-1)
1) 5√75 - 2√27 = 5√(25*3) - 2√(9*3) = 25√3 - 6√3 = 19√3
2) 3√20 + 5√45 - 2√80 = 3√(4*5) + 5√(9*5) - 2√(16*5) =
= 6√5 + 15√5 - 8√5 = 13√5
3) √176² - (112)²/98 = √(16*11)² - (16*7)²/(49*2) = 16*11 - (16² * 7²)/(7² * 2) =
= 2⁴ *11 - 2⁷ = 2⁴(11 - 2³) = 16*3 = 48
6<span>) √81a + √9a - √49a = 9√a + 3√a - 7√a = 5√a
9) 1/(5+2√6) + 1/(5-2√6) = </span><span>((5-2√6)+</span><span>(5+2√6)) / </span>(5-2√6)*<span><span><span><span>(5+2√6) =
= 10/(5² - (2√6)²) = 10/(25-24) = 10
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