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anonymous
 one year ago
Gabby solve {x^2}  x  20 = 0 as shown below:
\begin{array}{l}{x^2}  x  20 = 0\\\left( {x  5} \right)\left( {x + 4} \right) = 0\\x =  5,4\end{array}
Caitlyn says Gabby is wrong and believe this is the solution:
\begin{array}{l}{x^2}  x  20 = 0\\\left( {x  5} \right)\left( {x + 4} \right) = 0\\x = 5,  4\end{array}
Is Gabby or Caitlyn correct? Explain the error made by the incorrect girl.
anonymous
 one year ago
Gabby solve {x^2}  x  20 = 0 as shown below: \begin{array}{l}{x^2}  x  20 = 0\\\left( {x  5} \right)\left( {x + 4} \right) = 0\\x =  5,4\end{array} Caitlyn says Gabby is wrong and believe this is the solution: \begin{array}{l}{x^2}  x  20 = 0\\\left( {x  5} \right)\left( {x + 4} \right) = 0\\x = 5,  4\end{array} Is Gabby or Caitlyn correct? Explain the error made by the incorrect girl.

This Question is Closed

SolomonZelman
 one year ago
Best ResponseYou've already chosen the best response.0Well, first we have to know that when we say `a•b=0` (in general) THEN, either a or b has to be equal to 0. is this information correct?

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0by correct you mean the way it was typed ?

SolomonZelman
 one year ago
Best ResponseYou've already chosen the best response.0I mean that the point I made (as regards to the math part)

SolomonZelman
 one year ago
Best ResponseYou've already chosen the best response.0that the point I made is correct or not

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0{x^2}  x  20 = 0 this is the problem they are working out

SolomonZelman
 one year ago
Best ResponseYou've already chosen the best response.0yes, yes, I know.... I am asking you if you are {familiar with/ understand the} the zero product property

SolomonZelman
 one year ago
Best ResponseYou've already chosen the best response.0You know if you say `x • y = 0` then for it to be true, either x=0, or y=0

SolomonZelman
 one year ago
Best ResponseYou've already chosen the best response.0Ok, now back to our problem....

SolomonZelman
 one year ago
Best ResponseYou've already chosen the best response.0he factored the quadratic equation, and now he has: \(\large\color{black}{ \displaystyle (x5)(x+4)=0 }\)

SolomonZelman
 one year ago
Best ResponseYou've already chosen the best response.0Then, this "zero product property" (as I showed with `y•x=0`) has to work here too.

SolomonZelman
 one year ago
Best ResponseYou've already chosen the best response.0That means that either x5 =0 or that x+4 =0 Correct or not?

SolomonZelman
 one year ago
Best ResponseYou've already chosen the best response.0Now, for what value of x is x5=0? And for what value of x is x+4=0?

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0it would be 4, and 5 ?

SolomonZelman
 one year ago
Best ResponseYou've already chosen the best response.0Please in order, and please try again

SolomonZelman
 one year ago
Best ResponseYou've already chosen the best response.0x5=0 x+4=0 (5)5=0 (4)+4=0 according to what you said:

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0so the property that they did wrong was the zero property

SolomonZelman
 one year ago
Best ResponseYou've already chosen the best response.0One of them is correct. (But only one is correct, the other is wrong)

triciaal
 one year ago
Best ResponseYou've already chosen the best response.0dw:1437049882899:dw

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0so would Gabby be correcr ?

triciaal
 one year ago
Best ResponseYou've already chosen the best response.0dw:1437050014096:dw

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0so it would be Catilyn who is right ?

SolomonZelman
 one year ago
Best ResponseYou've already chosen the best response.0dw:1437050054286:dw

SolomonZelman
 one year ago
Best ResponseYou've already chosen the best response.0it seems as though you are trying to guess the answer....

SolomonZelman
 one year ago
Best ResponseYou've already chosen the best response.0x=4, x=5 that is correct
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