Question 310917: If one solution to the equation x^2 – 3x + k = 0 is 4, then what is the other solution?
a) -4 b) -1 c) 1
d) 4 e) cannot be determined from the information given
Answer by Edwin McCravy(20054)   (Show Source):
You can put this solution on YOUR website! If one solution to the equation x^2 – 3x + k = 0 is 4, then what is the other solution?
a) -4 b) -1 c) 1
d) 4 e) cannot be determined from the information given
x2 – 3x + k = 0
Since 4 is a solution, it must satisfy that equation when
4 is substituted for x. Substituting 4 for x in
x2 – 3x + k = 0
gives
(4)2 – 3(4) + k = 0
16 - 3(4) + k = 0
16 - 12 + k = 0
4 + k = 0
k = -4
Substituting -4 for k in
x2 – 3x + k = 0
gives
x2 – 3x + (-4) = 0
x2 – 3x - 4 = 0
(x - 4)(x + 1) = 0
x - 4 = 0, x + 1 = 0
x = 4, x = -1
So the other solution is -1, choice b)
Edwin
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