Algebra Formulas

In algebra formulas, an identity is an equation that is always true regardless of the values assigned to the variables. Algebraic Identity means that the left-hand side of the equation is identical to the right-hand side of the equation, and for all values of the variables. Algebraic identities find applications in solving the values of unknown variables. Here are some most commonly used algebraic identities:

• (a + b)² = a² + 2ab + b²
• (a - b)² = a² - 2ab + b²
• (a + b)(a - b) = a² - b²
• (x + a)(x + b) = x² + x(a + b) + ab

Let us look at the algebraic identity: (a + b)² = a² + 2ab + b², and try to understand this identity in algebra and also in geometry. As a proof of this formula, let us try to multiply algebrically the expression and try to find the formula. (a + b)² = (a + b) × (a + b) = a(a + b) + b(a + b) = a² + ab + ab + b². This expression can be geometrically understood as the area of the four sub figures of the below given square diagram. Further, we can consolidate the proof of the identity (a + b)²= a² + 2ab + b².

An important algebra formula introduced in class 10 is the “quadratic formula”. The general form of the quadratic equation is ax² + bx + c = 0, and there are two methods of solving this quadratic equation. The first method is to solve the quadratic equation by the algebraic method, and the second method is to solve through the use of the quadratic formula. The below formula is helpful to quickly find the values of the variable x with the least number of steps.

In the above expression, the value b² - 4ac is called the determinant and is useful to find the nature of the roots of the given equation. Based on the value of the determinant, the three types of roots are given below.

• If b² - 4ac > 0, then the quadratic equation has two distinct real roots.
• If b² - 4ac = 0,  then the quadratic equation has two equal real roots.
• If b² - 4ac < 0,  then the quadratic equation has two imaginary roots.

Apart from this, we have a few other formulas related to progressions. Progressions include some of the basic sequences such as arithmetic sequence and geometric sequence. The arithmetic sequence is obtained by adding a constant value to the successive terms of the series. The terms of the arithmetic sequence is a, a + d, a + 2d, a + 3d, a + 4d, .... a + (n - 1)d.  The geometric sequence is obtained by multiplying a constant value to the successive terms of the series. The terms of the geometric sequence are a, ar, ar², ar³, ar⁴, .....ar^n-1.  The below formulas are helpful to find the nth term and the sum of the terms of the arithmetic, and geometric sequence.

The important topics of Class 11 which have extensive use of algebraic formulas are permutations and combinations. Permutations help in finding the different arrangement of r things from the n available things, and combinations help in finding the different groups of r things from the available n things. The following formulas help in finding the permutations and combination values. 

Apart from the permutations and combinations, there is another important topic of “Binomial Theorem” as well which is used to evaluate the large exponents of algebraic expressions with two terms. Here the coefficients of the binomial terms are calculated from the formula of combinations. The below expression provides the complete formula for binomial expansion, and it can be termed as the algebraic expression of the binomial theorem.

The vector algebra formulas that are involved in class 12 are as follows. 

For any three vectors, \( \overrightarrow a\), \(\overrightarrow b \) and \(\overrightarrow c \):

• The magnitude of \(\overrightarrow a  = x \hat{i}+y \hat{j}+z \hat{k} \) is, \( |\overrightarrow a| = \sqrt{x^2+y^2+z^2} \).
• The unit vector along \(\overrightarrow a\) is \(\dfrac{\overrightarrow a }{|\overrightarrow a|}\).
• The dot product is defined as: \(\overrightarrow a \cdot \overrightarrow b = |\overrightarrow a| |\overrightarrow b| \cos \theta\), where \(\theta\) is the angle between the vectors \(\overrightarrow a\) and \(\overrightarrow b\).
• The cross product is defined as: \(\overrightarrow a \times \overrightarrow b = |\overrightarrow a| |\overrightarrow b| \sin \theta \,\,\hat{n}\), where \(\theta\) is the angle between the vectors \(\overrightarrow a \) and \(\overrightarrow b\).
• The scalar triple product of three vectors is given by \( [\overrightarrow a \text{  } \overrightarrow b \text{  } \overrightarrow c ] = \overrightarrow a \cdot (\overrightarrow b \times \overrightarrow c) = (\overrightarrow a \times \overrightarrow b) \cdot \overrightarrow c \).

An algebraic function is of the form y=f(x).  Here, x is the input and y is the output of this function. Here, each input corresponds to exactly one output. But multiple inputs may correspond to a single output. For example: f(x)= x² is an algebraic function. Here, when x=2, f(2)= 2² =4. Here, x=2 is the input, and f(2)=4 is the output of the function.

We can perform numerous arithmetic operations such as addition, subtraction, multiplication, and the dividing of fractions in algebra just the same way we do with fractions involving numbers. Further, it only has the unknown variables and involved the same rules of working across fractions. The below four expressions are useful for working with algebraic fractions. Adding Fractions:  x/y + z/w = (x.w + y.z)/(y.w)  

1. Subtracting Fractions: x/y - z/w = (x.w - y.z)/(y.w)

2. Multiplying Fractions: x/y × z/w  = xz/yw

3. Dividing Fractions: x/y ÷ z/w = x/y × w/z = xw/yz

Tips and Tricks

The following quick tips and tricks would be useful to easily understand the memorize algebraic identities.

1. You can memorize the algebraic identities by understanding how they are derived. For example, (a+b)²=(a+b)(a+b)= a²+ab+ab+b² = a²+2ab+b^2.
2. In the same way, you can try to derive the other algebraic identities as well.

Challenging Questions

What are the Algebraic Formulas?

Here are some most commonly used formulas of algebra:

• a² - b² =(a-b)(a+b)
• (a+b)² =a² + 2ab + b²
• (a-b)²=a² - 2ab+b²
• (x+a)(x+b)=x²+x(a+b)+a b 
• (a+b+c)²=a²+b²+c²+2ab+2bc+2ca
• (a+b)³ =a³ +3a²b+3ab² +b³
• (a - b)³ =a³ - 3a²b+3ab² - b³

Further, there are algebraic formulas for other topics of maths such as exponents, logarithms, permutations, sequences, and vector algebra.

What Are the Basic Algebraic Formulas in Math?

Here are some basic math formulas: 

• a² - b² =(a-b)(a+b)
• (a+b)² =a² + 2ab + b²
• (a-b)² = a² - 2ab + b² 
• (x+a)(x+b)=x² + x(a+b) + ab
• (a+b+c)² = a² + b² + c² + 2ab + 2bc + 2ca
• (a+b)³ =a³ +3a²b + 3ab² + b³
• (a-b)³ =a³ - 3a²b + 3ab²- b³

How do I Learn Algebra Formulas?

Algebra formulas can be easily memorized by visualizing the formulas as squares or rectangles. Further, the understanding of the factorized forms of the formulas helps to easily learn and remember the algebraic formulas.

What Is The Formula For a²- b² in Algebra Formulas?

The formula for a²- b² is (a+b)(a-b)= a²- b². It is called the difference of squares formula.

How to Solve Algebra Formulas?

The solving of algebra formulas is to aim at equalizing the left-hand side of the expression with the right-hand side of the expression. Further, the terms can be transferred from the left to the right side of the expression, based on the laws of algebra.

What is the Basis Of Algebra Formulas?

The basis of algebra formulas is that the resultant numeric value of the expressions on either side of the equals to sign is equal. Further, algebraically the terms are modified on either side to match up with the algebraic formulas.

What are Algebra Expressions?

For each of the algebra formulas, the equations with variables, powers, and arithmetic operations, and on either side of the equals to sign are called algebraic expressions. In the algebraic formula (a+b)(a-b)= a²- b², the terms on either side of the equals too sign is called an algebraic expression.

What are the Algebra Formulas for Triangular Numbers? 

The algebra formula for triangular numbers is H² = B² + A²  and it helps to relate the length of the sides of the triangle. It is applicable for a right triangle and has been derived from the Pythagaros theorem. The alphabets H represents the hypotenuse, B represents the base of the right triangle, and A represents the altitude of the triangle. Applying this same formula an example of triangular numbers is (6, 8, 10).