How do you factor #4u^2+9u-28#?

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Answer 1 · 2015-05-06T09:43:06

We can Split the Middle Term of this expression to factorise it

In this technique, if we have to factorise an expression like #au^2 + bu + c#, we need to think of 2 numbers such that:

#N_1*N_2 = a*c = 4*-28 = -112#
AND
#N_1 +N_2 = b = 9#

After trying out a few numbers we get #N_1 = 16# and #N_2 =-7#

#16*-7 = -112#, and #16+(-7)= 9#

#4u^2+9u-28 = 4u^2 +16u - 7u -28#

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

#(u+4)# is a common factor to each of the terms

#=color(green)((u+4)(4u-7)#