Examples with solutions for Solving Equations Using All Methods: Domain of definition

Exercise #1

3x:4y+6=6 \frac{3x:4}{y+6}=6

What is the field of application of the equation?

Video Solution

Step-by-Step Solution

To determine the field of application of the equation 3x:4y+6=6\frac{3x:4}{y+6}=6, we must identify values of yy for which the equation is defined.

  • The denominator of the given expression is y+6y + 6. In order for the expression to be defined, the denominator cannot be zero.
  • This leads us to solve the equation y+6=0y + 6 = 0.
  • Solving y+6=0y + 6 = 0 gives us y=6y = -6.
  • This means y=6y = -6 would make the denominator zero, thus the expression would be undefined for this value.

Therefore, the field of application, or the domain of the equation, is all real numbers except y=6y = -6.

We must conclude that y6 y \neq -6 .

Comparing with the provided choices, the correct answer is choice 3: y6 y \neq -6 .

Answer

y6 y\operatorname{\ne}-6

Exercise #2

25a+4b7y+43+2=9b \frac{25a+4b}{7y+4\cdot3+2}=9b

What is the field of application of the equation?

Video Solution

Step-by-Step Solution

To solve the problem, follow these steps:

  • Step 1: Understand that the equation 25a+4b7y+43+2=9b\frac{25a+4b}{7y + 4 \cdot 3 + 2}=9b is undefined when the denominator equals zero.
  • Step 2: Simplify the denominator: 7y+43+27y + 4 \cdot 3 + 2.
  • Step 3: Calculate the constant part: 43=124 \cdot 3 = 12, so the expression becomes 7y+12+27y + 12 + 2.
  • Step 4: Combine constants: 12+2=1412 + 2 = 14. The denominator is 7y+147y + 14.
  • Step 5: Set the denominator equal to zero to find values of yy that make the equation undefined: 7y+14=07y + 14 = 0.
  • Step 6: Solve for yy:
    • Subtract 14 from both sides: 7y=147y = -14.
    • Divide by 7: y=2y = -2.

Therefore, the equation is undefined when y=2y = -2. The field of application excludes y=2y = -2.

The choice that reflects this is y2\boxed{y \neq -2}.

Answer

y2 y\operatorname{\ne}-2

Exercise #3

x+y:32x+6=4 \frac{x+y:3}{2x+6}=4

What is the field of application of the equation?

Video Solution

Step-by-Step Solution

To solve this problem, we'll follow these steps to find the domain:

  • Step 1: Recognize that the expression x+y:32x+6=4\frac{x+y:3}{2x+6}=4 involves a fraction. The denominator 2x+62x + 6 must not be zero, as division by zero is undefined.
  • Step 2: Set the denominator equal to zero and solve for xx to find the values that must be excluded: 2x+6=02x + 6 = 0.
  • Step 3: Solve 2x+6=02x + 6 = 0:
    • 2x+6=02x + 6 = 0
    • 2x=62x = -6
    • x=3x = -3
  • Step 4: Conclude that the domain of the function excludes x=3x = -3, meaning x3x \neq -3.

Thus, the domain of the given expression is all real numbers except x=3x = -3. This translates to:

x3 x\operatorname{\ne}-3

Answer

x3 x\operatorname{\ne}-3

Exercise #4

6x+5=1 \frac{6}{x+5}=1

What is the field of application of the equation?

Video Solution

Step-by-Step Solution

To solve this problem, we will determine the domain, or field of application, of the equation 6x+5=1 \frac{6}{x+5} = 1 .

Step-by-step solution:

  • Step 1: Identify the denominator. In the given equation, the denominator is x+5 x+5 .
  • Step 2: Determine when the denominator is zero. Solve for x x by setting x+5=0 x+5 = 0 .
  • Step 3: Solve the equation: x+5=0 x+5 = 0 gives x=5 x = -5 .
  • Step 4: Exclude this value from the domain. The domain is all real numbers except x=5 x = -5 .

Therefore, the field of application of the equation is all real numbers except where x=5 x = -5 .

Thus, the domain is x5 x \neq -5 .

Answer

x5 x\operatorname{\ne}-5

Exercise #5

xyz2(3+y)+4=8 \frac{xyz}{2(3+y)+4}=8

What is the field of application of the equation?

Video Solution

Step-by-Step Solution

To find the domain of the given equation xyz2(3+y)+4=8 \frac{xyz}{2(3+y)+4}=8 , we need to ensure the denominator is not zero. This means solving 2(3+y)+4=0 2(3+y) + 4 = 0 .

Let's solve this step-by-step:

  • Step 1: Simplify the expression 2(3+y)+4=0 2(3+y) + 4 = 0 .
  • Step 2: Expand to 6+2y+4=0 6 + 2y + 4 = 0 .
  • Step 3: Combine like terms to get 2y+10=0 2y + 10 = 0 .
  • Step 4: Isolate the variable y y . Subtract 10 from both sides: 2y=10 2y = -10 .
  • Step 5: Divide by 2 to solve for y y : y=5 y = -5 .

If y=5 y = -5 , the denominator becomes zero, which makes the original expression undefined.

Therefore, the value of y y must not be 5-5 for the expression to be valid. In conclusion, the restriction on y y is that y5 y \neq -5 .

The correct answer choice is: y5 y \neq -5 .

Answer

y5 y\ne-5

Exercise #6

15+34:z4y12+8:2=5 \frac{\sqrt{15}+34:z}{4y-12+8:2}=5

What is the domain of the equation?

Video Solution

Step-by-Step Solution

To determine the field of application (domain of definition) of the given equation, we need to identify all values of the variables that would make the equation undefined.

The given equation is:
15+34:z4y12+8:2=5\frac{\sqrt{15}+34:z}{4y-12+8:2}=5

where the colon (:) represents division, so we can rewrite this as:
15+34z4y12+82=5\frac{\sqrt{15}+\frac{34}{z}}{4y-12+\frac{8}{2}}=5

Step 1: Identify potential division by zero in the numerator
In the numerator, we have the term 34z\frac{34}{z}. This expression is undefined when z=0z = 0.
Therefore, we must have: z0z \neq 0

Step 2: Simplify and analyze the denominator
The denominator is: 4y12+824y-12+\frac{8}{2}
Simplifying: 4y12+4=4y84y-12+4 = 4y-8

Step 3: Identify when the denominator equals zero
The entire fraction is undefined when the denominator equals zero:
4y8=04y-8 = 0
4y=84y = 8
y=2y = 2

Therefore, we must have: y2y \neq 2

Step 4: State the domain (field of application)
The equation is defined for all values of yy and zz except those that cause division by zero.

Therefore, the field of application of the equation is: z0z \neq 0 and y2y \neq 2

This corresponds to choice 3.

Answer

z0,y2 z\operatorname{\ne}0 , y\operatorname{\ne}2

Exercise #7

24:3t+424y+212+6=7z \frac{24:3t+4}{24y+21\cdot2+6}=7z

What is the domain of the equation?

Video Solution

Step-by-Step Solution

To find the domain of definition for this equation, we need to identify all values of the variables that would make the expression undefined. An expression becomes undefined when we have division by zero.

Let me first clarify the notation and rewrite the equation properly:
243t+424y+212+6=7z \frac{\frac{24}{3t}+4}{24y+21\cdot2+6}=7z

Now, let's identify where division by zero could occur:

Step 1: Analyze the numerator
The numerator is 243t+4 \frac{24}{3t}+4 . For this to be defined, we need:
3t0 3t \neq 0
Therefore: t0 t \neq 0

Step 2: Analyze the denominator
The denominator is 24y+212+6 24y+21\cdot2+6 . Let's simplify this:
24y+42+6=24y+48 24y + 42 + 6 = 24y + 48

For the entire fraction to be defined, we need:
24y+480 24y + 48 \neq 0
24y48 24y \neq -48
y2 y \neq -2

Step 3: State the domain restrictions
For the equation to be defined, both conditions must be satisfied simultaneously:

  • t0 t \neq 0 (to avoid division by zero in the numerator)
  • y2 y \neq -2 (to avoid division by zero in the main denominator)

Therefore, the domain of definition is: y2,t0 y \neq -2, t \neq 0

Answer

y2,t0 y\operatorname{\ne}-2 , t\operatorname{\ne}0