It is pretty cool to see that it is a quadratic equation after all:
Use (x + a)^3 = x^3 + 3ax^2 + 3a^2*x + a^3 with a=7
x^3 + 21x^2 + 147x + 343 = x^3 + 133 // - x^3 + 133
21x^2 + 147x + 210 = 0 // Let's divide it by 21
x^2 + 7x + 10 = 0
Now, I can see without the whole procedrue of solving a quadratic equation that
(x + 2)(x + 5) = 0
x1 = -2
x2 = -5
2007-03-08 22:18:38
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answer #1
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answered by Amit Y 5
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do u mean (x+7)^3 =x^3 + 133?
if so then u will need to expand (x+7)^3 either with the aid of a pascal triangle or using binomial expansion
so (x+7)^3=x^3+3(x^2)*7+3x(7^2)+7^3=x^3+21x^2+147x+343
so we have x^3+21x^2+147x+343=x^3 + 133
so 21x^2+147x+210=0
x^2+7x+10=0
(x+5)(x+2)=o
x=-5 or x=-2
2007-03-09 06:22:55
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answer #2
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answered by hiphop 2
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(x+7)^3 =x^3 + 133... three represents cube then this is the solution,
first, get (x+7)^2 which is (x^2+14x+49) multiply this by (x+7) to get (x+7)^3 equals to (x^3+21x^2+147x+343), equate this equation with x^3 + 133
x^3+21x^2+147x+343 = x^3 + 133
In general form, 21x^2+147x+210 = 0
divide this by 21, x^2+7x+10 = 0
by factorization, (x+5)(x+2)=0
x = -5 and -2
2007-03-09 07:06:57
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answer #3
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answered by reddish 3
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(x + 7)3 = x3 + 133
distribute
3x + 21 = 3x + 133
there is no solution
reductio ad absurdum
2007-03-09 06:16:47
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answer #4
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answered by Matthew P 4
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is it (x+7)* 3 ??
2007-03-09 06:32:18
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answer #5
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answered by sikunj.patel 2
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3(x+3)=3x+133
3x+9=3x+133
3x-3x=133-9
x dont exist
2007-03-09 07:25:40
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answer #6
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answered by dj opelac(shs II dalton) 1
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first of all you should know what is the value of x then i can answer your question!!
2007-03-09 06:12:48
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answer #7
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answered by Anonymous
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