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. The sides of the deck are 8, 15, and 17 feet.The first and simplest method of solving quadratic equations is the factorization method. Since \(x\) is a side of the triangle, \(x=−8\) does not It is a quadratic equation, so get zero on one side. Since this is a right triangle we can use the We are looking for the lengths of the sides Find the lengths of the sides of the deck. The length of one side will be 7 feet less than the length of the other side. Justine wants to put a deck in the corner of her backyard in the shape of a right triangle, as shown below. \(W=−5\) cannot be the width, since it's negative. Use the formula for the area of a rectangle. The area of the rectangular garden is 15 square feet. ![]() Restate the important information in a sentence. In problems involving geometric figures, a sketch can help you visualize the situation. The length of the garden is two feet more than the width. \)Ī rectangular garden has an area of 15 square feet.
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