How do you factor by grouping with three terms #252v + 48v ^2 -12v ^3#?

1 Answer
Apr 30, 2015

First simplify by extracting the obvious factor of #12v#
#252v+ 48v^2-12v^3#
#=12v(21+4v-v^2)#
or
#=(-12v)(v^2-4v-21)#

#21# can be factored as #3xx7#
and the difference between 3 and 7 is 4

so
#= (-12v)(v^2+3v-7v-21)#

#=(-12v)(v(v+3) - 7(v+3))#

#=(-12v)(v-7)(v+3)#