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ivann1987 [24]
3 years ago
5

How do you work out this problem using completing the square x2 - 4x - 80 = 0

Mathematics
2 answers:
Ugo [173]3 years ago
7 0

x^2 - 4x = 80

x^2 - 4x + 4 = 80 + 4 (Divide b, which is 4, by 2 and square it.)

x^2 - 4x + 4 = 84

sqrt(x + 2)^2 = sqrt(84)

x + 2 = plus or minus sqrt(84)

Subtract 2 from both sides

x = -2 plus or minus sqrt(84)

yulyashka [42]3 years ago
3 0

Answer:

A value that satisfies this equation is called a root, zero or solution of the equation!! We have three ... Solve each by factoring. 1) x2 + 4x -5 = 0 ... Follow the explanation and sample problem to review completing the square.

Step-by-step explanation:

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First multiply 57 x 30, then 30 x .35, then Ta da you have your answer (which is 598.5) 
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Step-by-step explanation:

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2 years ago
What is a the positive solution of x^2 - 36 =5x​
Minchanka [31]

Answer:

<h2>x = 9</h2>

Step-by-step explanation:

x^2-36=5x\qquad\text{subtract}\ 5x\ \text{from bot sides}\\\\x^2-5x-36=0\\\\x^2+4x-9x-36=0\qquad\text{distribute}\\\\x(x+4)-9(x+4)=0\\\\(x+4)(x-9)=0\iff x+4=0\ \vee\ x-9=0\\\\x+4=0\qquad\text{subtract 4 from both sides}\\\\x=-40

3 0
3 years ago
How do i solve this?<br>13=x/4​
Alex17521 [72]

Answer:

Rearrange the equation by subtracting what is to the right of the equal sign from both sides of the equation :  

                    13-(x/4)=0  

Step by step solution :

Step  1  :

           x

Simplify   —

           4

Equation at the end of step  1  :

       x

 13 -  —  = 0  

       4

Step  2  :

Rewriting the whole as an Equivalent Fraction :

2.1   Subtracting a fraction from a whole  

Rewrite the whole as a fraction using  4  as the denominator :  

          13     13 • 4

    13 =  ——  =  ——————

          1        4    

Equivalent fraction : The fraction thus generated looks different but has the same value as the whole  

Common denominator : The equivalent fraction and the other fraction involved in the calculation share the same denominator  

Adding fractions that have a common denominator :

2.2       Adding up the two equivalent fractions  

Add the two equivalent fractions which now have a common denominator

Combine the numerators together, put the sum or difference over the common denominator then reduce to lowest terms if possible:

13 • 4 - (x)     52 - x

————————————  =  ——————

     4             4    

Equation at the end of step  2  :

 52 - x

 ——————  = 0  

   4    

Step  3  :

When a fraction equals zero :

Now, to get rid of the denominator, Tiger multiple's both sides of the equation by the denominator. 3.1    When a fraction equals zero …

Where a fraction equals zero, its numerator, the part which is above the fraction line, must equal zero.

Here's how:

 52-x

 ———— • 4 = 0 • 4

  4  

Now, on the left hand side, the  4  cancels out the denominator, while, on the right hand side, zero times anything is still zero.

The equation now takes the shape :

  52-x  = 0  

Solving a Single Variable Equation :  

3.2      Solve  :    -x+52 = 0  

Subtract  52  from both sides of the equation :  

                     -x = -52  

Multiply both sides of the equation by (-1) :  x = 52  

7 0
3 years ago
Marco is studying a type of mold that grows at a fast rate. He created the function f(x) = 345(1.30)x to model the number of mol
Ivahew [28]

1.30 represents the rate of growth of the mold spores. This decimal is a representation of the percentage growth, which would be 130%.


Since the function is written in terms of weeks, x will equal 4 to represent the amount of spores after 4 weeks. Plug the value into the function:


345(1.30)^4 = \boxed{985.35}


Rounded to the nearest ones value, there will be 985 mold spores after 4 weeks.

8 0
3 years ago
Read 2 more answers
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