Hence, from the quadratic formula, we have: Question 4: Find the value of x: 27 x 2 − 12 = 0Ī) 2/3 B) ± 2/3 C) Ambiguous D) None of theseĪnswer : B) Here, a = 27, b = 0 and c = -12. Therefore, x = − 1 More Solved Examples For You The below image illustrates the best use of a quadratic equation.ĭiscriminant = b 2 − 4ac = 22 − 4×1×1 = 0 The quantity in the square root is called the discriminant or D. Just plug in the values of a, b and c, and do the calculations. We define it as follows: If ax 2 + bx + c = 0 is a quadratic equation, then the value of x is given by the following formula: This is the general quadratic equation formula. A method that will work for every quadratic equation. For such equations, a more powerful method is required. There are equations that can’t be reduced using the above two methods. This is known as the method of completing the squares. x – 3 = ☖ Which gives us these equations:.(x-3) 2 = 36 Take square root of both sides.Now we can write it as a binomial square: (b/2) 2 where ‘b’ is the new coefficient of ‘x’, to both sides as: x 2 – 6x + 9 = 27 + 9 or x 2 – 2×3×x + 32 = 36. Next, we make the left hand side a complete square by adding (6/2) 2 = 9 i.e. So dividing throughout by the coefficient of x 2, we have: 2x 2/2 – 12x/2 = 54/2 or x 2 – 6x = 27. In the next step, we have to make sure that the coefficient of x 2 is 1. In the standard form, we can write it as: 2x 2 – 12x – 54 = 0. Next let us get all the terms with x 2 or x in them to one side of the equation: 2x 2 – 12 = 54 Solution: Let us write the equation 2x 2=12x+54. Let us see an example first.Įxample 2: Let us consider the equation, 2x 2=12x+54, the following table illustrates how to solve a quadratic equation, step by step by completing the square. If we could get two square terms on two sides of the quality sign, we will again get a linear equation. In those cases, we can use the other methods as discussed below.īrowse more Topics under Quadratic Equationsĭownload NCERT Solutions for Class 10 Mathematics Completing the Square MethodĮach quadratic equation has a square term. This method is convenient but is not applicable to every equation. Solving these equations for x gives: x=-4 or x=1. Thus we have either (x+4) = 0 or (x-1) = 0 or both are = 0. For any two quantities a and b, if a×b = 0, we must have either a = 0, b = 0 or a = b = 0. Thus, we can factorise the terms as: (x+4)(x-1) = 0. Hence, we write x 2 + 3x – 4 = 0 as x 2 + 4x – x – 4 = 0. Consider (+4) and (-1) as the factors, whose multiplication is -4 and sum is 3. We do it such that the product of the new coefficients equals the product of a and c. Next, the middle term is split into two terms. Solution: This method is also known as splitting the middle term method. Examples of FactorizationĮxample 1: Solve the equation: x 2 + 3x – 4 = 0 Let’s see an example and we will get to know more about it. Hence, from these equations, we get the value of x. These factors, if done correctly will give two linear equations in x. Certain quadratic equations can be factorised. If you misunderstand something I said, just post a comment.The first and simplest method of solving quadratic equations is the factorization method. I can see that -12 * 1 makes -11 which is not what I want so I go with 12 * -1. I can clearly see that 12 is close to 11 and all I need is a change of 1. My other method is straight out recognising the middle terms. Here we see 6 factor pairs or 12 factors of -12. What you need to do is find all the factors of -12 that are integers. I use a pretty straightforward mental method but I'll introduce my teacher's method of factors first. So the problem is that you need to find two numbers (a and b) such that the sum of a and b equals 11 and the product equals -12. This hopefully answers your last question. The -4 at the end of the equation is the constant. In the standard form of quadratic equations, there are three parts to it: ax^2 + bx + c where a is the coefficient of the quadratic term, b is the coefficient of the linear term, and c is the constant.
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