Explanation

Substitute x = 1 and y = -1 into the expression:

13(x + y) = 13(1 + (-1)) = 13(0).

Therefore, 13(0) = 0.

Explanation

To convert 17 m/sec to km/hr:

1 m/sec = 3.6 km/hr

17 m/sec = 17 × 3.6 km/hr

= 61.2 km/hr

Explanation

• Realistic education system supports the scientific progress.
• It emphasizes empirical observation, critical thinking, and problem-solving skills, which are crucial for advancements in scientific fields.

Explanation

Educating an individual within a family often leads to broader benefits for the entire family unit.

The knowledge and skills gained by one family member can positively impact the dynamics, growth, and development of the entire family.

Explanation

The determinant is a unique real number associated with every square matrix.

It helps determine whether the matrix is invertible.

It is used in solving systems of equations.

Explanation

The formula to convert temperature from Celsius to Fahrenheit: T(°F) = 1.8T(°C) + 32

The formula to temperature convert Fahrenheit to Celsius: T(°C) = T(°F) - 32/1.8

Explanation

Let's calculate what needs to be added:

(7 + 2a - a² + 4a³) - (2a³ + a² - 3a - 1)

= 7 + 2a - a² + 4a³ - 2a³ - a² + 3a + 1

= 2a³ - 2a² + 5a + 8

Explanation

Let the son's present age be x.

The man's present age = 4x

In 5 years:

Son's age = x + 5

Man's age = 4x + 5

According to the problem:

4x + 5 = 3(x + 5)

4x + 5 = 3x + 15

4x - 3x = 15 - 5

x = 10

Explanation

Casein plastic is made by adding an acid (like vinegar) to milk, which causes the casein protein to form a solid.

This solid can be molded and dried to create a type of early plastic, known as casein plastic.

Explanation

Alliteration is the repetition of the same initial consonant sounds in nearby words.

In this line, the repeated "w" sound in wild, winds, whispered, willows shows alliteration.