EPT27a^2 - 21ab - 20b^2
is there anything that fits this? (a+b = -21 / a x b = -540) I cant find it.
Algebra? HALP!
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QuanticHawk
United States32026 Posts
27a^2 - 21ab - 20b^2 is there anything that fits this? (a+b = -21 / a x b = -540) I cant find it. | ||
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randombum
United States2378 Posts
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EmeraldSparks
United States1451 Posts
(-36)(15) = -540 Find the prime factorization of 540 and see if it has two factors which differ by 21 (as bonus one must be even other odd and both must have factor of three gogogo). | ||
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QuanticHawk
United States32026 Posts
2nd question, since my piece of shit online program doesnt show me how to do this one... Factor the following by first factoring out the greatest common factor then factoring the trinomial that remains. x^2 (5x + 9) + 4x (5x + 9) + 3 (5x + 9) | ||
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randombum
United States2378 Posts
27a^2 - 21ab - 20b^2 <--- I don't understand what that means with no A, B, or =. Unless we are solving for a+b = -21 / a x b = -540 for A and B and just plugging in the numbers. But then why is a+b = -21 / a x b = -540 in parentheses | ||
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EmeraldSparks
United States1451 Posts
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pachi
Melbourne5338 Posts
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QuanticHawk
United States32026 Posts
edit: thanks es and pachi | ||
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QuanticHawk
United States32026 Posts
ima post some more tomorrow. im callin it a night. | ||
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QuanticHawk
United States32026 Posts
factor x^6 - 4096 i got (x^3-64)(x^3+64). why is it telling me this is wrong? >< same thing for x^4 - 256 i got (x^2-16)(x^2+16), isn't that correct? | ||
Chill
Calgary25954 Posts
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QuanticHawk
United States32026 Posts
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[r]h_probe
United States188 Posts
you get (x^2-16)(x^2+16) then (x-4)(x+4)(x^2+16) for x^6-4096 you started off fine just keep going | ||
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Jonoman92
United States9101 Posts
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QuanticHawk
United States32026 Posts
this is prime, correct? also clueless as to what to do here: x^2 + 4bx - 7ax - 28ab | ||
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EmeraldSparks
United States1451 Posts
You should also try and separate terms like the second into two terms of two and see if they share a common factor (which is easier to see once you write them separately.) | ||
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fight_or_flight
United States3988 Posts
http://www.purplemath.com/modules/specfact2.htm x^6 - 4096 = (-4 + x) (4 + x) (16 - 4 x + x^2) (16 + 4 x + x^2) x^4 - 256 = (-4 + x) (4 + x) (16 + x^2) 4x^2 - 4x + 1 - 25b^2 = -(1 + 5 b - 2 x) (-1 + 5 b + 2 x) x^2 + 4bx - 7ax - 28ab = prime?? | ||
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