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anonymous
 one year ago
Let u = x^2+ 3. Which equation is equivalent to (x^2+3)^2+ 21 = 10x^2+ 30 in terms of u?
anonymous
 one year ago
Let u = x^2+ 3. Which equation is equivalent to (x^2+3)^2+ 21 = 10x^2+ 30 in terms of u?

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campbell_st
 one year ago
Best ResponseYou've already chosen the best response.0well factor the right hand side of the equation and you get \[(x^2 + 3)^2 + 21 = 10(x^2 + 3)\] since \[u = x^2 + 3\] the equation becomes \[(u)^2 + 21 = 10(u)\] now just simplify

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0Wait I typed in the equation incorrectly. I'm sorry. It was: Let u = x^2+ 3. (x^2+3)^2+ 21 = 10(x^2+ 30)

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0Wait no. I'm sorry give me a second

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0Sorry! it was originally correct, but what happened to the 30?

campbell_st
 one year ago
Best ResponseYou've already chosen the best response.0ok then so the left side is straight forward rewrite \[u = x^2 + 3~~~as~~~ x^2 = u  3\] so the right side becomes \[10(x^2 + 30) = 10([u^2  3] + 30)\] hope that helps

campbell_st
 one year ago
Best ResponseYou've already chosen the best response.0oops should read \[10([u  3] + 30)\]

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0Okay I get it now! And the answer is u^210u+21?

campbell_st
 one year ago
Best ResponseYou've already chosen the best response.0well you have on the right side 10[u 3] + 30) = 10(u + 27) = 10u + 270 you can check to make sure

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0woah.. you lost me now

campbell_st
 one year ago
Best ResponseYou've already chosen the best response.0the problem becomes \[u^2 + 21 = 10([u  3] + 30) ~~~or~~~~u^2 + 21 = 10(u + 27)\] so distribute and collect like terms.
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