Решаем!
Задание 4.1
\[\sqrt{a^2 + 8ab + 16b^2}\] при \(a = 3\frac{3}{7}, b = \frac{1}{7}\)
\[\sqrt{\left(3\frac{3}{7}\right)^2 + 8 \cdot 3\frac{3}{7} \cdot \frac{1}{7} + 16 \cdot \left(\frac{1}{7}\right)^2} = \sqrt{\left(\frac{24}{7}\right)^2 + 8 \cdot \frac{24}{7} \cdot \frac{1}{7} + 16 \cdot \frac{1}{49}} = \sqrt{\frac{576}{49} + \frac{192}{49} + \frac{16}{49}} = \sqrt{\frac{784}{49}} = \sqrt{16} = 4\]
Задание 4.2
\[\sqrt{a^2 + 12ab + 36b^2}\] при \(a = 7\frac{2}{5}, b = \frac{3}{5}\)
\[\sqrt{\left(7\frac{2}{5}\right)^2 + 12 \cdot 7\frac{2}{5} \cdot \frac{3}{5} + 36 \cdot \left(\frac{3}{5}\right)^2} = \sqrt{\left(\frac{37}{5}\right)^2 + 12 \cdot \frac{37}{5} \cdot \frac{3}{5} + 36 \cdot \frac{9}{25}} = \sqrt{\frac{1369}{25} + \frac{1332}{25} + \frac{324}{25}} = \sqrt{\frac{3025}{25}} = \sqrt{121} = 11\]
Задание 4.3
\[\sqrt{a^2 + 10ab + 25b^2}\] при \(a = 1\frac{6}{13}, b = \frac{4}{13}\)
\[\sqrt{\left(1\frac{6}{13}\right)^2 + 10 \cdot 1\frac{6}{13} \cdot \frac{4}{13} + 25 \cdot \left(\frac{4}{13}\right)^2} = \sqrt{\left(\frac{19}{13}\right)^2 + 10 \cdot \frac{19}{13} \cdot \frac{4}{13} + 25 \cdot \frac{16}{169}} = \sqrt{\frac{361}{169} + \frac{760}{169} + \frac{400}{169}} = \sqrt{\frac{1521}{169}} = \sqrt{9} = 3\]
Задание 4.4
\[\sqrt{a^2 + 8ab + 16b^2}\] при \(a = 3\frac{2}{3}, b = \frac{1}{3}\)
\[\sqrt{\left(3\frac{2}{3}\right)^2 + 8 \cdot 3\frac{2}{3} \cdot \frac{1}{3} + 16 \cdot \left(\frac{1}{3}\right)^2} = \sqrt{\left(\frac{11}{3}\right)^2 + 8 \cdot \frac{11}{3} \cdot \frac{1}{3} + 16 \cdot \frac{1}{9}} = \sqrt{\frac{121}{9} + \frac{88}{9} + \frac{16}{9}} = \sqrt{\frac{225}{9}} = \sqrt{25} = 5\]
Задание 4.5
\[\sqrt{9a^2 + 6ab + b^2}\] при \(a = \frac{5}{13}, b = 6\frac{11}{13}\)
\[\sqrt{9 \cdot \left(\frac{5}{13}\right)^2 + 6 \cdot \frac{5}{13} \cdot 6\frac{11}{13} + \left(6\frac{11}{13}\right)^2} = \sqrt{9 \cdot \frac{25}{169} + 6 \cdot \frac{5}{13} \cdot \frac{89}{13} + \left(\frac{89}{13}\right)^2} = \sqrt{\frac{225}{169} + \frac{2670}{169} + \frac{7921}{169}} = \sqrt{\frac{10816}{169}} = \sqrt{64} = 8\]
Задание 4.6
\[\sqrt{16a^2 + 8ab + b^2}\] при \(a = \frac{3}{11}, b = 5\frac{10}{11}\)
\[\sqrt{16 \cdot \left(\frac{3}{11}\right)^2 + 8 \cdot \frac{3}{11} \cdot 5\frac{10}{11} + \left(5\frac{10}{11}\right)^2} = \sqrt{16 \cdot \frac{9}{121} + 8 \cdot \frac{3}{11} \cdot \frac{65}{11} + \left(\frac{65}{11}\right)^2} = \sqrt{\frac{144}{121} + \frac{1560}{121} + \frac{4225}{121}} = \sqrt{\frac{5929}{121}} = \sqrt{49} = 7\]
Задание 4.7
\[\sqrt{25a^2 + 10ab + b^2}\] при \(a = \frac{4}{9}, b = 3\frac{7}{9}\)
\[\sqrt{25 \cdot \left(\frac{4}{9}\right)^2 + 10 \cdot \frac{4}{9} \cdot 3\frac{7}{9} + \left(3\frac{7}{9}\right)^2} = \sqrt{25 \cdot \frac{16}{81} + 10 \cdot \frac{4}{9} \cdot \frac{34}{9} + \left(\frac{34}{9}\right)^2} = \sqrt{\frac{400}{81} + \frac{1360}{81} + \frac{1156}{81}} = \sqrt{\frac{2916}{81}} = \sqrt{36} = 6\]
Задание 4.8
\[\sqrt{36a^2 + 12ab + b^2}\] при \(a = \frac{4}{5}, b = 8\frac{1}{5}\)
\[\sqrt{36 \cdot \left(\frac{4}{5}\right)^2 + 12 \cdot \frac{4}{5} \cdot 8\frac{1}{5} + \left(8\frac{1}{5}\right)^2} = \sqrt{36 \cdot \frac{16}{25} + 12 \cdot \frac{4}{5} \cdot \frac{41}{5} + \left(\frac{41}{5}\right)^2} = \sqrt{\frac{576}{25} + \frac{1968}{25} + \frac{1681}{25}} = \sqrt{\frac{4225}{25}} = \sqrt{169} = 13\]
Задание 4.9
\[\sqrt{a^2 - 6ab + 9b^2}\] при \(a = 3, b = 6\)
\[\sqrt{3^2 - 6 \cdot 3 \cdot 6 + 9 \cdot 6^2} = \sqrt{9 - 108 + 324} = \sqrt{225} = 15\]
Задание 4.10
\[\sqrt{a^2 - 12ab + 36b^2}\] при \(a = 8, b = 3\)
\[\sqrt{8^2 - 12 \cdot 8 \cdot 3 + 36 \cdot 3^2} = \sqrt{64 - 288 + 324} = \sqrt{100} = 10\]
Задание 4.11
\[\sqrt{a^2 - 8ab + 16b^2}\] при \(a = 4, b = 3\)
\[\sqrt{4^2 - 8 \cdot 4 \cdot 3 + 16 \cdot 3^2} = \sqrt{16 - 96 + 144} = \sqrt{64} = 8\]
Задание 4.12
\[\sqrt{a^2 - 10ab + 25b^2}\] при \(a = 7, b = 2\)
\[\sqrt{7^2 - 10 \cdot 7 \cdot 2 + 25 \cdot 2^2} = \sqrt{49 - 140 + 100} = \sqrt{9} = 3\]
Задание 4.13
\[\sqrt{a^2 + 10ab + 25b^2}\] при \(a = 8, b = -2\)
\[\sqrt{8^2 + 10 \cdot 8 \cdot (-2) + 25 \cdot (-2)^2} = \sqrt{64 - 160 + 100} = \sqrt{4} = 2\]
Задание 4.14
\[\sqrt{a^2 + 6ab + 9b^2}\] при \(a = 5, b = -4\)
\[\sqrt{5^2 + 6 \cdot 5 \cdot (-4) + 9 \cdot (-4)^2} = \sqrt{25 - 120 + 144} = \sqrt{49} = 7\]
Задание 4.15
\[\sqrt{a^2 + 12ab + 36b^2}\] при \(a = 7, b = -3\)
\[\sqrt{7^2 + 12 \cdot 7 \cdot (-3) + 36 \cdot (-3)^2} = \sqrt{49 - 252 + 324} = \sqrt{121} = 11\]
Задание 4.16
\[\sqrt{a^2 + 4ab + 4b^2}\] при \(a = 2, b = -4\)
\[\sqrt{2^2 + 4 \cdot 2 \cdot (-4) + 4 \cdot (-4)^2} = \sqrt{4 - 32 + 64} = \sqrt{36} = 6\]
Ответ: 4.1) 4; 4.2) 11; 4.3) 3; 4.4) 5; 4.5) 8; 4.6) 7; 4.7) 6; 4.8) 13; 4.9) 15; 4.10) 10; 4.11) 8; 4.12) 3; 4.13) 2; 4.14) 7; 4.15) 11; 4.16) 6
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