- #1
velox_xox
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I managed to get the other problems right, but this one I've been fiddling with and can't seem to get the right answer.
[tex] \sqrt {3b -2} - \sqrt {2b + 5} = 1 [/tex]
Answer: [itex] 22 [/itex]
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For this I tried the method of leaving the equation as is and squaring both sides, since this is the way the textbook seems to want me to learn it for this lesson.
[itex] \sqrt {3b - 2} - \sqrt {2b + 5} = 1 [/itex]
[itex] (\sqrt {3b - 2} - \sqrt {2b + 5})^2 = 1^2 [/itex]
[itex] 3b - 2 - 2\sqrt {6b^2 - 10} + 2b + 5 = 1 [/itex]
[itex] 5b + 3 - 2\sqrt {6b^2 - 10} = 1 [/itex]
[itex] 5b + 3 = 2\sqrt {6b^2 - 10} [/itex]
[itex] (5b + 3)^2 = (2\sqrt {6b^2 - 10})^2 [/itex]
[itex]25b^2 + 30b + 9 = 4(6b^2 - 10) [/itex]
[itex] 25b^2 + 30b + 9 = 24b^2 - 40 [/itex]
[itex] b^2 + 30b +49 = 0 [/itex]
At this point, I realize that 22 isn't a factor of that final equation. I've also tried the other methods, such as [itex] \sqrt {3b - 2} = \sqrt {2b + 5} [/itex], and I get b = 7.
I've tried to look through it for obvious arithmetic mistakes or my tendency to create incorrect products of the form (a + b)^2, but I didn't see anything. It could be the sheer volume of the problem has me spooked or tripping up.
Any help would be greatly appreciated. Thanks in advance.
Homework Statement
[tex] \sqrt {3b -2} - \sqrt {2b + 5} = 1 [/tex]
Answer: [itex] 22 [/itex]
Homework Equations
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The Attempt at a Solution
For this I tried the method of leaving the equation as is and squaring both sides, since this is the way the textbook seems to want me to learn it for this lesson.
[itex] \sqrt {3b - 2} - \sqrt {2b + 5} = 1 [/itex]
[itex] (\sqrt {3b - 2} - \sqrt {2b + 5})^2 = 1^2 [/itex]
[itex] 3b - 2 - 2\sqrt {6b^2 - 10} + 2b + 5 = 1 [/itex]
[itex] 5b + 3 - 2\sqrt {6b^2 - 10} = 1 [/itex]
[itex] 5b + 3 = 2\sqrt {6b^2 - 10} [/itex]
[itex] (5b + 3)^2 = (2\sqrt {6b^2 - 10})^2 [/itex]
[itex]25b^2 + 30b + 9 = 4(6b^2 - 10) [/itex]
[itex] 25b^2 + 30b + 9 = 24b^2 - 40 [/itex]
[itex] b^2 + 30b +49 = 0 [/itex]
At this point, I realize that 22 isn't a factor of that final equation. I've also tried the other methods, such as [itex] \sqrt {3b - 2} = \sqrt {2b + 5} [/itex], and I get b = 7.
I've tried to look through it for obvious arithmetic mistakes or my tendency to create incorrect products of the form (a + b)^2, but I didn't see anything. It could be the sheer volume of the problem has me spooked or tripping up.
Any help would be greatly appreciated. Thanks in advance.