Solve the equation: 2x^2 + 3x = 14.

This is a quadratic equation, for these types of questions it is often easiest to try and rearrange the formula into the form ax^2 + bx + c = 0, where a, b and c are whole numbers. Therefore the first thing to do would be to take 14 away from both sides of the equation. This would leave us with 2x^2 + 3x - 14 = 0. Now that it is in the form that we want, we can start to factorise the equation (put into brackets). I find it easiest if we focus firstly on 2x^2, the only two whole numbers that can multiply together to make 2x^2 are 2x and x (as 2 times x times x is 2x^2). This means we know what the brackets start with, (2x...) and (x...).
The next step would be to focus on the last number in the equation, this would be -14. We can then write the numbers that multiply to make -14. -14 and 1, -7 and 2, -2 and 7, -1 and 14. Looking at what we have in the brackets, we know that using a 14 in the equation would not produce a 3x, therefore we are left with (7 and -2) and (2 and -7). If we then try out these number in different combinations in our brackets, we will find that the only combination that produces a +3x is (2x +7)(x-2). (As (-2)2 = -4 and 7 times 1 = 7 and then 7+(-4) = 3. Therefore the factorised equation is (2x + 7)(x - 2) = 0. If this equals 0, one of the brackets must equal 0 (as 0 multiplied by anything is still 0). If x-2=0 then x=2, alternatively if 2x+7=0 then x=-3.5, therefore x = 2 or -3.5

Related Maths GCSE answers

All answers ▸

200 pupils are taking a school trip. Some are flying, some are taking the bus. There are three times as many boys going as girls. One third of the boys going are flying. How many boys are getting the bus?


Find the coordinates and the point of intersection between the lines 8x + 7y = 11 and y = 5x + 2


John has £385 he wants to give to Charlie, Ben and Sarah. He gives them the money in the ratio 1:2:4 respectively. How much money does each person get?


Given 2 points, how do you calculate the equation of a straight line?