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In-s [12.5K]
3 years ago
11

Please help. Don’t understand this math problem!

Mathematics
1 answer:
oksian1 [2.3K]3 years ago
5 0

Answer:

  { 4 }

Step-by-step explanation:

First you need to solve the equation. Then you need to write the solutions as a set.

__

I like to use a graphing calculator to solve equations involving roots. That helps avoid extraneous solutions. Here, the graph of the left side intersects the graph of the right side at x=4. There is exactly one solution, so the solution set is ...

  { 4 }

__

Solving this algebraically, you would isolate the radical, then "undo" it by squaring both sides of the equation. Then solve the resulting quadratic. That will have 2 solutions, only one of which will work in the original equation.

  √(5x +16) -2 = 3x -8 . . . . given

  √(5x +16) = 3x -6 . . . . . .  add 2

  5x +16 = (3x -6)^2 . . . . .  square both sides

  5x +16 = 9x^2 -36x +36 . . . . expand the square

  9x^2 -41x +20 = 0 . . . . . . subtract (5x+16) to put into standard form

Factors of 9·20 = 180 that have a sum of 41 are 5 and 36, so we can rewrite this equation as ...

  9x^2 -36x -5x +20 = 0

  9x(x -4) -5(x -4) = 0 . . . . . . factor by pairs

  (9x -5)(x -4) = 0

The values of x that make this equation true are the values that make the factors be zero: 5/9 and 4. Trying these in the equation, we find ...

  √(5(5/9) +16) -2 = 13/3 -2 = 2 1/3 . . . . value of the left side for x = 5/9

  3(5/9) -8 = -6 1/3 . . . . . . value of the right side for x=5/9; not the same

  x = 5/9 is NOT A SOLUTION

__

  √(5(4)+16) -2 = √36 -2 = 4 . . . . value of the left side for x = 4

  3(4) -8 = 12 -8 = 4 . . . . . . value of the right side for x=4. These are the same, so ...

  x = 4 is a solution

The set of solutions is then ...

  { 4 } . . . . . solution set

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An artificial lake is in the shape of a rectangle and has an area of 9/20 square mile the width of the lake is 1/5 the length of
DIA [1.3K]
Answer:  The dimensions are:   " 1.5 mi.  ×  ³⁄₁₀  mi. " .
_______________________________________________
             { length = 1.5 mi. ;  width =  ³⁄₁₀  mi. } .
________________________________________________
Explanation:
___________________________________________
Area of a rectangle:

A = L * w ; 

in which:  A = Area = (9/20) mi.² ,
                L = Length = ?
                w = width = (1/5)*L = (L/5) = ?
________________________________________
  A = L * w ;  we want to find the dimensions; that is, the values for
                         "Length (L)"  and "width (w)" ; 
_______________________________________
Plug in our given values:
_______________________________________
 (9/20) mi.² = L * (L/5) ;  in which: "w = L/5" ; 
 
     → (9/20) = (L/1) * (L/5) = (L*L)/(1*5) = L² / 5 ;
   
          ↔  L² / 5  = 9/20 ;
 
            →  (L² * ? / 5 * ?) = 9/20 ?    

                →     20÷5 = 4 ;  so; L² *4 = 9 ;
 
                   ↔    4 L² = 9 ; 
 
                   →  Divide EACH side of the equation by "4" ;
           
                   →   (4 L²) / 4 = 9/4 ;
______________________________________
           to get:  →  L² = 9/4 ; 
 Take the POSITIVE square root of each side of the equation; to isolate "L" on one side of the equation; and to solve for "L" ;
___________________________________________          
 
     →   ⁺√(L²)   =   ⁺√(9/4) ;

    →   L  =  (√9) / (√4) ; 

    →  L = 3/2 ; 

    → w = L/5 = (3/2) ÷ 5 = 3/2 ÷ (5/1) = (3/2) * (1/5) = (3*1)/(2*5) = 3/10;
________________________________________________________
Let us check our answers:
_______________________________________
(3/2 mi.) * (3/10 mi.) =? (9/20) mi.² ??

→ (3/2)mi. * (3/10)mi.  =  (3*3)/(2*10) mi.² = 9/20 mi.² ! Yes!
______________________________________________________
So the dimensions are: 

Length = (3/2) mi. ;  write as: 1.5 mi.

width = ³⁄₁₀ mi.
___________________________________________________
or; write as:  " 1.5 mi.  ×  ³⁄₁₀ mi. " .
___________________________________________________
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Answer:

C

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What is this please help?
mestny [16]

Answer:

y = 2/3x - 1

Step-by-step explanation:

The simpliest way to determine the slope of the line is to see the rise over run of the line. In this case, we are given two points which are at (0, -1) and (3,1)

By calculating rise of run, we can see that the starting point goes up by 2 units, from -1 to 1 and goes to the right 3 units, from 0 to 3

In this case, that means we have a slope of 2/3x.

The +b plays into the y-intercept of the line, which is actually the same of one of our points: (0,-1)

Since this number is a negative, it would actually be y = (2/3)x + (-1) which is the same as y=2/3x - 1

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