You can put this solution on YOUR website! 6r^2-60r+126
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Common factor: 6
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= 6(r^2-10r+21)
Think of two numbers whose product is 21 and whose sum is -10.
The numbers are -7 and -3
Replace -10r by -7r-3r
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= 6(r^2-7r-3r+21)
Factor the 1st 2 and the last 2 terms separately.
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= 6[(r(r-7)-3(r-7)]
Factor again:
= 6[(r-7)(r-3)]
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Cheers,
Stan H.
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