Jawaban:
14.
[tex]5 \sqrt{28} + \sqrt{252} - 4 \sqrt{112} \\ =5 \sqrt{4 \times 7} + \sqrt{36 \times 7} - 4 \sqrt{16 \times 7} \\ = 10 \sqrt{7} + 6 \sqrt{7} - 16 \sqrt{7} \\ = (10 + 6 - 16) \sqrt{7} = 0[/tex]
15.
[tex]3 \sqrt{12} + \sqrt{48} \times 3 \sqrt{3 } \\ = 3 \sqrt{4 \times 3} + \sqrt{16 \times 3} \times 3 \sqrt{3} \\ = 6 \sqrt{3} + (4 \sqrt{3} \times 3 \sqrt{3} ) = 6 \sqrt{3} + 36[/tex]
16.
[tex]3 \sqrt{8} - 2 \sqrt{32} + 4 \sqrt{18} \\ = 3 \sqrt{4 \times 2} - 2 \sqrt{16 \times 2} + 4 \sqrt{9 \times 2} \\ = 6 \sqrt{2} - 8 \sqrt{2} + 12 \sqrt{2} \\ = (6 - 8 + 12) \sqrt{2} = 10 \sqrt{2} [/tex]
17. B.-9√5
[tex] \sqrt{45} - 3 \sqrt{80} \\ = \sqrt{9 \times 5} - 3 \sqrt{16 \times 5} \\ = 3 \sqrt{5} - 12 \sqrt{5} \\ = - 9 \sqrt{5} [/tex]
18. D.√5
[tex]3 \sqrt{45} + \sqrt{20} - 2 \sqrt{125} \\ = 3 \sqrt{9 \times 5} + \sqrt{4 \times 5} - 2 \sqrt{25 \times 5} \\ = (9 + 2 - 10) \sqrt{5} = \sqrt{5} [/tex]
19.A.6√7
[tex]2 \sqrt{28} - \sqrt{63} + \sqrt{175} \\ = 2 \sqrt{4 \times 7} - \sqrt{9 \times 7} + \sqrt{25 \times 7} \\ = (4 - 3 + 5) \sqrt{7} = 6 \sqrt{7} [/tex]
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