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2 votes
(c-30)(c-120)=184 how do I solve it

2 Answers

3 votes

(c-30)(c-120)=184\\ c^2-120c-30c+3600=184\\ c^2-150c+3416=0\\ c^2-150c+5625-2209=0\\ (c-75)^2=2209\\ c-75=√(2209) \vee c-75=-√(2209)\\ c=75+47 \vee c=75-47\\ c=122 \vee c=28
5 votes

(c-30)(c-120)=184\ \ \ \ | multiply \ both\ brackets\\\\ c^2-120c-30c+3600=184\ \ \ \ | subtract\ 184\\\\ c^2-150c+3416=\ \ \ \ | factorisation\\\\c^2-122c-28c+3416 \\\\(c-122)(c-28)=0\\\\c=122\ \ or\ \ \ c=28
User Giles Bathgate
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