Question

what must be added to 49 y square + 70 xy to make it a perfect square
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Answer 1

Answer:

$25x {}^{2}$

Step-by-step explanation:

$49y {}^{2} + 70xy$

25x^{2} must be added to make it a perfect square.

$(7y) {}^{2} + 2 \times 7 \times 5xy + (5x) {}^{2} - 25x {}^{2} = (7y + 5x) {}^{2} - 25x {}^{2}$