2√3 + √6 = 2 * 1,732 + 2,45 ≈ 3,464 + 2,45 ≈ 5,914
2√3 + √3*√2 = √3(2+√2)
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2х + 5 = 8х - 1
2х -8х = -1 - 5
-6х = - 6
х = 1
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7√3 - √21 = 7√3 - √3 *√7 = √3(7-√7)