pakai jalannya tlng dibantu

[tex]7 \sqrt{7} \times \sqrt{14} \\ = 7 \sqrt{7 \times 14} \\ = 7 \sqrt{7 \times 7 \times 2} \\ = 7 \sqrt{ {7}^{2} \times 2} \\ = 7 \times 7 \sqrt{2} \\ = 49 \sqrt{2} [/tex]
jadi jawabannya C

semoga membantu