SOLUTION: 3x + 7 = x^2 + k = 7x + 15 That's the question. It has 2 (=) signs, how do you solve for k?

Algebra ->  Algebra  -> Equations -> SOLUTION: 3x + 7 = x^2 + k = 7x + 15 That's the question. It has 2 (=) signs, how do you solve for k?      Log On

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Question 71107: 3x + 7 = x^2 + k = 7x + 15
That's the question. It has 2 (=) signs, how do you solve for k?
Answer by checkley75(3666) About Me  (Show Source):
You can put this solution on YOUR website!
3x+7=7x+15
3x-7x=15-7
-4x=8
x=8/-4
x=-2 now substitute -2 for x in the middle equation
-2^2+k=7*-2+15
4+k=-14+15
k=-14+15-4
k=-3 answer.
proof
3*-2+7= -2^2-3
-6+7=4-3
1=1