
Find the value of is:


Important Points to Remember in Chapter -1 - Square-Square Root and Cube-Cube Root from Arihant Expert Team Mathematics & Pedagogy CTET & TETs Class (VI-VIII) Solutions
Square-Square Root and Cube-Cube Root
Square: If is a number then it’s square is represented by raised to the power , i.e., and its square root is expressed as ' where √’ is called radical. The value under the root symbol is said to be radicand.
Note:
1. equal to
2. Square of positive numbers are always positive in nature.
3. The square of negative numbers is also positive in nature. For example,
4. Square of zero is zero
5. The square of the root of a number is equal to the value under the root. For example,
6. The unit place of square of any even number will have an even number only.
7. If a number has or in the unit’s place, then its square ends in .
8. If a number has or in the unit’s place, then its square ends in .
9. A number having or at unit’s place is never a perfect square. In other words, no square number ends in or .
10. For any natural number m greater than , is a Pythagorean triplet.
11. Squares of even numbers are always even numbers and square of odd numbers are always odd.
12. The Square of a natural number other than one is either a multiple of or exceeds a multiple of by . In other words, a perfect square leaves the remainder or on division by .
Procedure to check whether a given natural number is a perfect square or not.
Step I: Obtain the natural number.
Step II: Write the number as a product of prime factors.
Step III: Group the factors in pairs in such a way that both the factors in each pair are equal.
Step IV: See whether some factor is left over or not. If no factor is left over in the grouping, then the given number is a perfect square. Otherwise, it is not a perfect-square.
Step V: To obtain the number whose square is the given number taken over one factor from each group and multiply them.
Square Roots: The square root of a number a is that number which when multiplied by itself gives a as the product. Thus, if b is the square root of a number a, then or . The square root symbol is . It follows from this that
i.e. b is the square root of a if and only if a is the square of b.
Properties of Square Roots
Property 1: If the units digit of a number is 2, 3, 7 or 8, then it does not have root in N (the set of natural numbers).
Property 2: If a number ends in an odd number of zeros, then it does not have a square root. If a square number is followed by an even number of zeros, it has a square root in which the number of zeros in the end is half the number of zeros in the number.
Property 3: The square root of an even square number is even and that root of an odd square number is odd.
Property 4: If a number has a square root in N, then its unit digit must be 0, 1, 4, 5, or 9.
Property 5: Negative numbers have no square root in the system of rational numbers.
is not a rational number. It will be a complex number.
Property 6: The sum of first odd numbers is .
Square Root by Prime Factorization Method
Step I: Obtain the given number.
Step II: Resolve the given number into prime factors by successive division.
Step III: Make pairs of prime factors such that both the factors in each pair are equal. Since the number is a perfect square, you will be able to make an exact number of pairs of prime factors.
Step IV: Take one factor from each pair.
Step V: Find the product of factors obtained in step IV.
Step VI: The product obtained in step V is the required square root.
Square Root of Rational Numbers in the Form of Fractions:
Step I: Obtain the fraction
Step II: If the given square root of the numerator and the denominator are the square roots of numerator and denominator respectively of the given fraction.
Step III: Find the square root of the numerator and denominator separately.
Step IV: Obtain the fraction whose numerator and denominator are the square roots of numerator and denominator respectively of the given fraction.
Step V: The fraction obtained in Step IV is the square root of the given fraction.
Cube of Numbers: The number with exponent 3 is called cube.
The word ‘cube’ is used in geometry. A cube is a solid figure which has all its sides equal.
There are only ten perfect cubes from 1 to 1000.
If a number is a number, then the cube of a is
Some Properties of Cubes of Natural Numbers are:-
Property 1: Cubes of all even numbers are even.
Property 2: Cubes of all odd natural numbers are odd.
Property 3: The sum of the cubes of first n natural numbers is equal to the square of their sum.
Property 4: Cubes of the numbers ending in digit 1, 4, 5, 6 and 9 are the numbers ending in the same digit.
Cube Root: A number is the cube root of a number , if .
In other words, the cube-root of a number n is that number whose cube gives .
The cube-root of a number is denoted by . is also called a radical, is called the radicand and is called the index of the radical.
Here;
Cube Root by Prime Factorization
Step I: Obtain the given number.
Step II: Resolve it into prime factors.
Step III: Group the factors in in such a way that each number of the group is same.
Step IV: Take one factor from each group.
Step V: Find the product of the factors obtained in step IV. This product is the required cube root.
Cube-root of rational-numbers: