Answer
$(3a+5)(2a+7b)$
Work Step by Step
Group the four terms into two sets of parentheses and pull out the greatest common factors in each.
$6a^2+10a+21ab+35b$
$=(6a^2+10a)+(21ab+35b)$
$=2a(3a+5)+7b(3a+5)$
$=(3a+5)(2a+7b)$
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