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Bas_tet [7]
3 years ago
9

Which value of b will cause the quadratic equation x^2+bx+5=0 to have two real number solution

Mathematics
2 answers:
Westkost [7]3 years ago
7 0

Answer:

Every value of b>4.47 and b<-4.47 will cause the quadratic equation x^2+bx+5=0 to have two real number solution.

Step-by-step explanation:

We have the quadratic function x^2+bx+5=0, and we have to find the value of b.

A <em>quadratic function</em> is ax^2+bx+c=0, a\neq 0, a quadratic function usually has two real solutions. You can find that solutions using Bhaskara's Formula:

x_1=\frac{-b+\sqrt{b^2-4.a.c} }{2.a}

x_2=\frac{-b-\sqrt{b^2-4.a.c} }{2.a}

x_1 and x_2 are real solutions of the quadratic equation if and only if:

b^2-4.a.c >0

If b^2-4.a.c the quadratic equation doesn't have real solutions.

If  b^2-4.a.c =0  the quadratic equation has only one solution.

Then in this case to have two real number solutions: b^2-4.a.c >0

We have x^2+bx+5=0, where a=1, b, c=5

Then,

b^2-4.a.c >0\\b^2-4.1.5>0\\b^2-20>0

Adding 20 in both sides of the equation:

b^2-20>0\\b^2-20+20>20\\b^2>20\\b>\sqrt{20}

Which is the same as: b

Then, b>\sqrt{20}\\b>4.47\\b

Then every value of b>4.47 and b<-4.47 will cause the quadratic equation x^2+bx+5=0 to have two real number solution.

For example b=-5 or b=5.

If you replace with b=-5 in b^2-4.a.c >0

b^2-4.a.c >0\\(-5)^2-4.1.5>0\\25-20>0\\5>0

Then the quadratic function has two real number solutions.

Aloiza [94]3 years ago
5 0
To have 2 real number solutions  the discriminant b^2 - 4ac  must be greater than zero.

so the condition  for 2 real roots in this equation is:-

b^2 - 4*1*5 > 0
b^2 >  20

b > sqrt 20    ( positive root)    Answer
You might be interested in
A+b=180<br> A=-2x+115<br> B=-6x+169<br> What is the value of B?
natulia [17]
The answer is:  " 91 " .   
___________________________________________________
                    →    " B = 91 " .
__________________________________________________ 

Explanation:
__________________________________________________
Given:  
__________________________________________________
    "  A +  B = 180 " ;

  "A =  -2x + 115 " ;   ↔  A =  115 − 2x ;  

  "B = - 6x + 169 " ;  ↔  B = 169 − 6x ;  
_____________________________________________________
METHOD 1)
_____________________________________________________
Solve for "x" ; and then plug the solved value for "x" into the expression given for "B" ; to  solve for "B"
_____________________________________________________

(115 − 2x) + (169 − 6x) = 

  115 − 2x + 169 − 6x = ?

→ Combine the "like terms" ;  as follows:

      + 115 + 169 = + 284 ; 

 − 2x − 6x = − 8x ; 
_________________________________________________________
And rewrite as:

 " − 8x + 284 " ; 
_________________________________________________________
   →  " - 8x + 284 = 180 " ; 

Subtract:  "284" from each side of the equation:

  →  "  - 8x + 284 − 284 = 180 − 284 " ; 

to get:

 →  " -8x = -104 ; 

Divide EACH SIDE of the equation by "-8 " ; 
    to isolate "x" on one side of the equation; & to solve for "x" ; 

→ -8x / -8 = -104/-8 ; 

→  x = 13
__________________________________________________________
Now, to find the value of "B" :
__________________________________________________________
  "B = - 6x + 169 " ;  ↔  B = 169 − 6x ;  

↔  B = 169 − 6x ;  

         = 169 − 6(13) ;   ===========> Plug in our "solved value, "13",  for "x" ;

         = 169 − (78) ; 

         = 91 ;

   B   = " 91 " .
__________________________________________________
The answer is:  " 91 " . 
____________________________________________________
     →     " B = 91 " . 
____________________________________________________
Now;  let us check our answer:
____________________________________________________
               →   A + B = 180 ;  
____________________________________________________
Plug in our "solved answer" ; which is "91", for "B" ;  as follows:
________________________________________________________

→  A + 91 = ? 180? ;  

↔  A = ? 180 − 91 ? ; 

→  A = ?  -89 ?  Yes!
________________________________________________________
→  " A =  -2x + 115 " ;   ↔  A =  115 − 2x ;  

Plug in our solved value for "x"; which is: "13" ; 

" A = 115 − 2x " ; 

→  A = ? 115 − 2(13) ? ;

→  A = ? 115 − (26) ? ; 

→  A = ? 29 ? Yes!
_________________________________________________ 
METHOD 2)
_________________________________________________
Given:  
__________________________________________________
    "  A +  B = 180 " ;

  "A =  -2x + 115 " ;   ↔  A =  115 − 2x ;  

  "B = - 6x + 169 " ;  ↔  B = 169 − 6x ; 

→  Solve for the value of "B" :
_______________________________________________________
 A + B = 180 ;  

→ B = 180 − A ; 

→ B = 180 − (115 − 2x) ; 

→ B = 180 − 1(115 − 2x) ;  ==========> {Note the "implied value of "1" } ; 
__________________________________________________________
Note the "distributive property" of multiplication:__________________________________________________  a(b + c)  = ab +  ac ;  <u><em>AND</em></u>:
  a(b − c)  = ab − ac .________________________________________________________
Let us examine the following part of the problem:
________________________________________________________
              →      " − 1(115 − 2x)  " ; 
________________________________________________________

→  "  − 1(115 − 2x) " = (-1 * 115) − (-1 * 2x) ;

                                =  -115 − (-2x) ;
                         
                                =  -115  +  2x ;        
________________________________________________________
So we can bring down the:  " {"B = 180 " ...}"  portion ; 

→and rewrite:
_____________________________________________________

→  B = 180 − 115 + 2x ; 

→  B = 65 + 2x ; 
_____________________________________________________
Now;  given:   "B = - 6x + 169 " ;  ↔  B = 169 − 6x ; 

→ " B =  169 − 6x  =  65 + 2x " ; 
______________________________________________________
→  " 169 − 6x  =  65 + 2x "

Subtract "65" from each side of the equation;  & Subtract "2x" from each side of the equation:

→  169 − 6x − 65 − 2x  =  65 + 2x − 65 − 2x ; 

to get:

→   " - 8x + 104 = 0 " ;
 
Subtract "104" from each side of the equation:

→   " - 8x + 104 − 104 = 0 − 104 " ;

to get: 

→   " - 8x = - 104 ;

Divide each side of the equation by "-8" ; 
   to isolate "x" on one side of the equation; & to solve for "x" ; 

→  -8x / -8  = -104 / -8 ; 

to get:

→  x =  13 ; 
______________________________________________________

Now, let us solve for:  " B " ;  → {for which this very question/problem asks!} ; 

→  B = 65 + 2x ;  

Plug in our solved value, " 13 ",  for "x" ; 

→ B = 65 + 2(13) ; 

        = 65 + (26) ;  

→ B =  " 91 " .
_______________________________________________________
Also, check our answer:
_______________________________________________________
Given:  "B = - 6x + 169 " ;   ↔  B = 169 − 6x = 91 ; 

When "x  = 13 " ; does: " B = 91 " ? 

→ Plug in our "solved value" of " 13 " for "x" ;

      → to see if:  "B = 91" ; (when "x = 13") ;

→  B = 169 − 6x ; 

         = 169 − 6(13) ; 

         = 169 − (78)______________________________________________________
→ B = " 91 " . 
______________________________________________________
6 0
2 years ago
There are some beads in the box. 40% of them were blue and the rest were red. Adam used all the blue beads and 25% of the red be
Shalnov [3]

Answer:

65% of the beads were used to make the bracelet.

Step-by-step explanation:

40% of the beads were blue which means 60% of the beads were red. If all the blue beads were used that means 40% was used so you add the 25% of the red beads that were used which is why the answer is 65%.

7 0
2 years ago
Pls help math problem is hard
vazorg [7]

Answer:

Reflect over y axis and go 7 units down.

Step-by-step explanation:

It will match the triangles.

7 0
2 years ago
Find the center and the radius of the circle defined by the equation x^2-8x+y+12y+36=0
choli [55]
Hello,
center is (4,-6)
radius=4
since
x^2-8x+y^2+12y+36=0\\&#10;&#10;x^2-2*4x+16-16+y^2+2*6y+36=0\\&#10;&#10;(x-4)^2+(y+6)^2=4^2&#10;&#10;


3 0
3 years ago
If the endpoints of the diameter of a circle are (−8, −6) and (−4, −14), what is the standard form equation of the circle? A) (x
Andrei [34K]

Answer:

\large\boxed{A.\ (x+6)^2+(y+10)^2=20}

Step-by-step explanation:

The standard form of an equation of a circle:

(x-h)^2+(y-k)^2=r^2

(h, k) - center

r - radius

We have the endpoints of the diameter of a circle (-8, -6) and (-4, -14).

The midpoint of a diameter is a center of a circle.

The formula of a midpoint:

\left(\dfrac{x_1+x_2}{2},\ \dfrac{y_1+y_2}{2}\right)

Substitute:

x=\dfrac{-8+(-4)}{2}=\dfrac{-12}{2}=-6\\\\y=\dfrac{-6+(-14)}{2}=\dfrac{-20}{2}=-10

We have h = -6 and k = -10.

The radius is the distance between a center and the point on a circumference of a circle.

The formula of a distance between two points:

d=\sqrt{(x_2-x_1)^2+(y_2-y_1)^2}

Substitute (-6, -10) and (-8, -6):

r=\sqrt{(-8-(-6))^2+(-6-(-10))^2}=\sqrt{(-2)^2+4^2}=\sqrt{4+16}=\sqrt{20}

Finally we have

(x-(-6))^2+(y-(-10))^2=(\sqrt{20})^2\\\\(x+6)^2+(y+10)^2=20

5 0
3 years ago
Read 2 more answers
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