1. Find which of the variables [tex]\(x, y, z,\)[/tex] and [tex]\(u\)[/tex] represent rational numbers and which represent irrational numbers:

(i) [tex]\(x^2 = 5\)[/tex]

(ii) [tex]\(y^2 = 9\)[/tex]

(iii) [tex]\(z^2 = 0.04\)[/tex]

(iv) [tex]\(u^2 = \frac{17}{4}\)[/tex]



Answer :

To determine whether each of the given variables represents a rational or irrational number, follow these steps:

### Step 1: Solve for the values

(i) [tex]\( x^2 = 5 \)[/tex]

First, solve for [tex]\( x \)[/tex]:
[tex]\[ x = \sqrt{5} \][/tex]
The square root of 5 is approximately 2.23606797749979.

(ii) [tex]\( y^2 = 9 \)[/tex]

Next, solve for [tex]\( y \)[/tex]:
[tex]\[ y = \sqrt{9} \][/tex]
The square root of 9 is exactly 3.0.

(iii) [tex]\( z^2 = 0.04 \)[/tex]

Then, solve for [tex]\( z \)[/tex]:
[tex]\[ z = \sqrt{0.04} \][/tex]
The square root of 0.04 is 0.2.

(iv) [tex]\( u^2 = \frac{17}{4} \)[/tex]

Finally, solve for [tex]\( u \)[/tex]:
[tex]\[ u = \sqrt{\frac{17}{4}} \][/tex]
The square root of [tex]\( \frac{17}{4} \)[/tex] is approximately 2.0615528128088303.

### Step 2: Determine Rationality or Irrationality

(i) [tex]\( x = \sqrt{5} \approx 2.23606797749979 \)[/tex]

The value of the square root of 5 is not a rational number since it cannot be expressed as a simple fraction. Therefore, [tex]\( x \)[/tex] is irrational.

(ii) [tex]\( y = \sqrt{9} = 3.0 \)[/tex]

The value of the square root of 9 is a whole number (3). Since whole numbers are rational, [tex]\( y \)[/tex] is rational.

(iii) [tex]\( z = \sqrt{0.04} = 0.2 \)[/tex]

The value of the square root of 0.04 is 0.2, which can be expressed as a fraction (1/5). Since it can be written as a fraction with integer numerator and non-zero integer denominator, [tex]\( z \)[/tex] is rational.

(iv) [tex]\( u = \sqrt{\frac{17}{4}} \approx 2.0615528128088303 \)[/tex]

The value of the square root of [tex]\( \frac{17}{4} \)[/tex] is not a rational number since it cannot be expressed as a simple fraction. Therefore, [tex]\( u \)[/tex] is irrational.

### Conclusion

Thus, the classifications are as follows:
- [tex]\( x \)[/tex] is irrational.
- [tex]\( y \)[/tex] is rational.
- [tex]\( z \)[/tex] is rational.
- [tex]\( u \)[/tex] is irrational.