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 #1
avatar+1250 
+1

 

Jessica baked 72 cookies and sold x cookies. Max baked 36 cookies and sold half as many cookies as Jessica did. How many cookies did Jessica sell if they each had the same number of cookies left over?    

 

Call "n" the number of cookies they each had left over.    

 

                                                                72 – x  =  n         (1)     

 

                                                                36 – x/2  =  n      (2)     

 

Subtract (2) from (1)                                36 – x/2  =  0             

 

                                                                        x/2  =  36   

 

                                                                           x  =  72   

 

So                                                        Jessica sold 72 cookies    

                                                             Max        sold 36 cookies     

                                                             and neither had any cookies left over (i.e., n = 0).    

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20 août 2023
 #1
avatar+1250 
+1

 

For what value of $h$ does the quadratic $7x^2 + 5x = h + 6x^2 - 3x$ have exactly one real solution in $x$?    

 

                                                      7x^2 + 5x = h + 6x^2 - 3x

 

                                                      7x2 – 6x2 + 5x + 3x – h  =  0

 

Combine units.                                  x2 + 8x – h  =  0     

 

This is in the form                             ax2 + bx + c

 

To have only one solution means  

that the expression is a square.  

For it to be a square, then                b2 – 4ac has to equal zero.       

 

                                                          82 – (4)(1)(–h)  =  0    

 

                                                           64 + 4h  =  0  

 

                                                                   4h  =  –64    

 

                                                                     h  =  –16   

 

Check Answer   

 

Substitute –16 into the   

quadratic equation.                  x2 + 8x –(–16)   

 

                                                x2 + 8x + 16   

 

Will this factor?  Yes.               (x + 4)(x +  4)   

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18 août 2023