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 #2
avatar+2447 
+1

 

In regard to #1 above "...the value of k that makes the equation have exactly one solution is k = 3/2."  

 

I think that solution was for the value of x, instead of for the value of k.  

 

I followed as far as "...one solution when the discriminant b^2 - 4ac = 0."  So far, so good. 
 

At that point, I think I would substitute values in             b2 – 4ac  =  0  

 

                                                                            (6)2 – (4)(2)(k)  =  0  

 

                                                                                        36 – 8k  =  0  

 

                                                                                                8k  =  36  

 

                                                                                                  k  =  36/8  

 

                                                                                                  k  =  9/2  

I don't know how to check the veracity  

of this answer.  If I'm wrong, I would truly  

appreciate someone showing me where.  

.

Jun 12, 2023
 #1
avatar+2447 
+1

 

How do you find the vertex of y=x^2+10x-21?  

 

The first derivitive is the slope

of the curve at any point.                         y' = 2x + 10  

 

When the slope is zero, it means  

the curve is neither increasing nor  

decreasing, so set the first derivitive  

equal to zero and solve for x                     2x + 10  =  0  

                                                                         2x  =  –10  

                                                                          x  =  –5    This is the x-coordinate.  

 

Substitute –5 back into the 

original equation                                      y  =  x2 + 10x – 21  

                                                                y  =  (–5)2 + (10)(–5) – 21  

                                                                y  =  25 – 50 – 21  

                                                                y  =  –46           This is the y-coordinate.  

 

So the vertex of the parabola is at           (–5 , –46)  

 

You can take the original equation y=x^2+10x-21  

to the Desmos Graphing Calculator and see it  

drawn.  That's how I checked my answer.   

.

Jun 12, 2023
 #1
avatar+2447 
+1

 

Will and Grace are canoeing on a lake.  Will rows at 50 meters per minute and Grace rows at 20 meters per minute. Will starts rowing at 2 p.m. from the west end of the lake, and Grace starts rowing from the east end of the lake at 2 p.m. If they always row directly towards each other, and the lake is 3800 meters across from the west side of the lake to the east side, at what time will the two meet?  

 

Will's rate is 50 m/min.  

Grace's rate is 20 m/min.  

 

They're rowing toward each other,  

so their rate of closure is 70 m/min.  

 

The lake is 3800 meters across.  

 

The time it will take them to meet is given by  

                                                                                    Distance  

                                                                            T  =  –––––––  

                                                                                       Rate  

 

                                                                                    3800 m  

                                                                            T  =  –––––––  

                                                                                    70 m/min  

 

The time it takes them to meet                             T  =  54.29 min  

 

The time on the clock is          2:00 pm + 54.29 min  =  2:54:17  

 

(The :17 is because 0.29 minute is 17 seconds.)  

 

Jun 12, 2023
Jun 11, 2023

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