Question

$8 \sqrt{45} - 6 \sqrt{20} + \sqrt{245} - 4 \sqrt{125}$
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Answer 1

8√45 - 6√20 + √245 - 4√125

= 8×3×√5 - 6×2×√5 + 7×√5 - 4×5×√5

= √5(24 - 12 + 7 - 20)

= √5(-1)

= -√5