How do you factor the trinomial #7u^2+26u-8#?

1 Answer
Safi
Oct 21, 2016

#(7u-2)(u+4)#

Explanation:

#color(red)(7)u^2+color(blue)26ucolor(red)(-8)#

For expansion, first
multiply #color(red)7# with #color(red)(-8)#, which is #=-56#, then

Find 2 numbers whose product is #-56# and sum is #color(blue)26#, that is #color(green)28# and #color(green)(-2)#.

Factorization by expansion :
#7u^2+color(green)(28u-2u)-8#

Now, take common on first 2 terms and last 2 terms seperately,
#7u(u+4)-2(u+4)#

Further, taking common on #(u+4)#:
#(7u-2)(u+4)#

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