The expression #16x^2-106x-105# can be written as #(8x + a)(2x + b)#, where #a# and #b# are integers. What is #a + 2b#?

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Question from AoPS. Please help!
I tried to do it and figured out that a+4b=-53 but...
yeah. anyways.

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Answer 1 · 2018-06-04T21:13:41

-23

If you factorise it (or you could use the formula) you get

#(8x+7)(2x-15)#

This gives a=7 and b=-15
a+2b=7-30=-23