SOLUTION: 1. Find the value of C if 2xy-6x+7y+c is factorable

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Question 18338: 1. Find the value of C if 2xy-6x+7y+c is factorable
Answer by Earlsdon(6294) About Me  (Show Source):
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Find the value of c that will make 2xy-6x%2Bc factorable.
Try factoring by grouping.
%282xy-6x%29+%2B+%287y%2Bc%29 Factor 2x from the left set of parentheses.
2x%28y-3%29+%2B+%287y%2Bc%29 Factor a 7 from the second set of parentheses.
2x%28y-3%29+%2B+7%28y%2Bc%2F7%29 Now set %28y%2Bc%2F7%29+=+%28y-3%29 and solve for c.
y%2Bc%2F7+=+y-3 Subtract y from both sides.
c%2F7+=+-3 Multiply both sides by 7.
c+=+-21
Answer: c = -21
Check: Factor by grouping;
%282xy-6x%29%2B%287y-21%29+=+2x%28y-3%29+%2B+7%28y-3%29 = %282x%2B7%29%28y-3%29