-9 times -7 will get you the same product as 9 times 7 which is 63...
remember when multiplying two negatives you get a positive.
Sqrt -13 = sqrt13 i
sqrt -26 = sqrt2 * sqrt13i
sqrt-13 * sqrt -26 = sqrt2 * 13* i^2 = -13 sqrt2 (because i^2 = -1)
answer is -13 sqrt2
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