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

Exercise #1

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 #2

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 #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

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 #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 field of application of the equation?

Video Solution

Step-by-Step Solution

To solve this problem, we need to identify the values of yy for which the denominator of the expression becomes zero, as these values are not part of the domain.

First, let's simplify the denominator of the given equation:

Original equation: 15+34z4y12+82=5 \frac{\sqrt{15} + \frac{34}{z}}{4y - 12 + \frac{8}{2}} = 5

Simplifying the terms: 34:z remains as it is for simplification purposes, and 82=4 34:z \text{ remains as it is for simplification purposes, and } \frac{8}{2} = 4

Thus, the denominator becomes: (4y12+4)=4y8 (4y - 12 + 4) = 4y - 8

We need to ensure the denominator is not zero to avoid undefined expressions: 4y80 4y - 8 \neq 0

Simplify and solve for yy: 4y80    4y8    y2 4y - 8 \neq 0 \implies 4y \neq 8 \implies y \neq 2

Therefore, the equation is undefined for y=2y = 2, and the answer is that the field of application excludes y=2y = 2.

Given the possible choices for the problem, the correct choice is: y2 y\operatorname{\ne}2

The solution to this problem is y2 y \neq 2 .

Answer

y2 y\operatorname{\ne}2