How do you solve #5r^2 - 44r + 120 = -30 + 11r# by factoring?

1 Answer
Sudip Sinha
Aug 9, 2015

# r = 5, 6 #

Explanation:

# 5 r^2 - 44 r + 120 = -30 + 11 r #
# => 5 r^2 - 55 r + 150 = 0 # (Adding # 30 - 11 r # to both sides)
# => r^2 - 11 r + 30 = 0 # (Dividing by 5)
# => r^2 - 5 r - 6 r + 30 = 0 # (Noting that # 30 = 5 * 6 #, and that # 5 + 6 = 11 #)
# => r ( r - 5 ) - 6 ( r - 5 ) = 0 #
# => ( r - 5 ) ( r - 6 ) = 0 #
# => r = 5 # or # r = 6 #

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