How do I factor out a constant before factoring out a quadratic? Factor completely: 3w^2-3w-90

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asked Nov 23, 2015 223k views

4 votes

How do I factor out a constant before factoring out a quadratic?
Factor completely: 3w^2-3w-90

Mathematics
high-school

Peyman Abdollahy asked

by Peyman Abdollahy

7.4k points

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1 Answer

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$3w^2-3w-90 =0 \ \ \:3 \\ \\w^2- w-30 =0 \\ \\a=1 , \ b= -1 , c= -30 \\ \\\Delta =b^2-4ac = (-1)^2 -4\cdot1\cdot (-30) =1+120=121 \\ \\w_(1)=(-b-√(\Delta) )/(2a)=(1-√(121))/(2 )=( 1-11)/(2)=(-10)/(2)=-5$

$w_(2)=(-b+√(\Delta) )/(2a)=(1+√(121))/(2 )=( 1+11)/(2)=(12)/(2)=6 \\ \\ Answer:\\ \\ w^2- w-30 =(x+5)(x-6)$

Kvadiyatar answered Nov 29, 2015