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anonymous
 one year ago
Use completing the square to solve (x + 7)(x – 9) = 25 for x.
anonymous
 one year ago
Use completing the square to solve (x + 7)(x – 9) = 25 for x.

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SolomonZelman
 one year ago
Best ResponseYou've already chosen the best response.0first expand the product. (x+7)(x9) = ?

SolomonZelman
 one year ago
Best ResponseYou've already chosen the best response.0yes, (x + 7)(x – 9) = 25 x\(^2\)9x+7x63 = 25 add the x's on the left side, x\(^2\)2x63 = 25

SolomonZelman
 one year ago
Best ResponseYou've already chosen the best response.0Add 63 to both sides, and u then get?

SolomonZelman
 one year ago
Best ResponseYou've already chosen the best response.0x\(^2\)2x63 = 25 x\(^2\)2x63\(\small\color{red}{+63}\)= 25\(\small\color{red}{+63}\)

SolomonZelman
 one year ago
Best ResponseYou've already chosen the best response.0like that, add 63 to both sides. what do you get after doing this?

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0ooooooooooh i see. x^22x= 88

SolomonZelman
 one year ago
Best ResponseYou've already chosen the best response.0yes, and then tell me what number would make the x²2x +what a perfect square trinomial? (remember the rule DanJS posted: "half of the coefficient on x, then squared")

SolomonZelman
 one year ago
Best ResponseYou've already chosen the best response.0that number that makes the left hand side a perfect square trinomial, this number, you should add to both sides of the equation.

SolomonZelman
 one year ago
Best ResponseYou've already chosen the best response.0So, add 1 to both sides

SolomonZelman
 one year ago
Best ResponseYou've already chosen the best response.0x\(^2\)2x\(\small\color{blue}{+1}\)= 88\(\small\color{blue}{+1}\)

SolomonZelman
 one year ago
Best ResponseYou've already chosen the best response.0can you go on from here? steps just in case: \(1.\) simplify the right side \(2.\) factor the left side (it should look like " (xnumber)² ") \(3.\) take the square root of both sides (and don't forget the \(\pm\)) \(4.\) add 1 to both sides of the equation
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