#3 ways to solve a quadratic equation how to#

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. Now we use our algebra skills to solve for 'x'.The first and simplest method of solving quadratic equations is the factorization method. Total time = time upstream + time downstream = 3 hours (to travel 8 km at 4 km/h takes 8/4 = 2 hours, right?) We can turn those speeds into times using: when going downstream, v = x+2 (its speed is increased by 2 km/h).when going upstream, v = x−2 (its speed is reduced by 2 km/h).Let v = the speed relative to the land (km/h)īecause the river flows downstream at 2 km/h:.Let x = the boat's speed in the water (km/h).There are two speeds to think about: the speed the boat makes in the water, and the speed relative to the land: What is the boat's speed and how long was the upstream journey? The negative value of x make no sense, so the answer is:Įxample: River Cruise A 3 hour river cruise goes 15 km upstream and then back again. The desired area of 28 is shown as a horizontal line. Let us solve this one by Completing the Square. How many you sell depends on price, so use 'P' for Price as the variable what is the best price? And how many should you make? at $350, you won't sell any bikes at all.$700,000 for manufacturing set-up costs, advertising, etcīased on similar bikes, you can expect sales to follow this 'Demand Curve':.Now you want to make lots of them and sell them for profit. You have designed a new style of sports bicycle! So the ball reaches the highest point of 12.8 meters after 1.4 seconds. Then find the height using that value (1.4)

The method is explained in Graphing Quadratic Equations, and has two steps:įind where (along the horizontal axis) the top occurs using −b/2a: Note: You can find exactly where the top point is! The factors of −15 are: −15, −5, −3, −1, 1, 3, 5, 15īy trying a few combinations we find that −15 and 1 work

Multiply to give a×c, and add to give b' method in Factoring Quadratics: There are many ways to solve it, here we will factor it using the 'Find two numbers that It looks even better when we multiply all terms by −1: (Note for the enthusiastic: the -5t 2 is simplified from -(½)at 2 with a=9.8 m/s 2)Īdd them up and the height h at any time t is:Īnd the ball will hit the ground when the height is zero: Gravity pulls it down, changing its position by about 5 m per second squared: It travels upwards at 14 meters per second (14 m/s): (Note: t is time in seconds) The height starts at 3 m: Ignoring air resistance, we can work out its height by adding up these three things: