The area of this rectangle is 56 cm2 length = 3k+2 and width = 7 - Find the value of k

The first step in answering any maths question is to identify key words or key information. Key information is area, length and width. We have been told that the total area is 56cm2. We know that area is length mutliplied by width.  We have been told length is equivalent to 3k+2 and width = 7. Therefore to obtain the area we need to multiply length times width so 7 multiplied by 3x+2. This when we multiply 3k+2 we need to put brackets around it (3k+2). When we multiply a number by a bracket it looks like so- 7(3k+2).  So length multiplied by width = area therefore 7(2k+2) = 56. The first step in an equation like this is to get rid of the number in front of the bracket. Also in any equation what you do to one side (left side) you do to the other side (right). To get rid of the 7 you need to divide it by itself so you would divide 7(3k+2) by 7. This will clear the 7 as 7/7  =1 but this has no impact on the number in the brackets. YOu also have to do the same on the other side. Therefore you will divide 56 by 7 = 8

what you are left with is 3k+2 = 8 and the equation becomes easier to solve. The next step is to get the factor of 'k' on its own on that side so you will need to get rid of the + 2. To get rid of +2 you will need to take away 2 from each side. SO you will be left with 3k = 6. Finally you will need to get k on its own therefore you will be need to divide each side by 3 and you will be left with k=2. So the main lession to be learnt is that  what you do to one side of the equation you do the other side. 

AB

Related Maths GCSE answers

All answers ▸

John ran a race at his school. The course was measured at 450m correct to 2sf and his time was given at 62 econds to the nearest second. Calculate the difference between his maximum and minimum possible average speed. Round you answer to 3sf.


How do you calculate arc length and sector area and why is it calculated like this? You are given sector angle 40 degrees and radius 7cm and asked to give answers to 3sf.


Solve this simultaneous equation: 2 + 5y = 3x, x + y = 6


Solve the quadratic equation 3x^2 + x – 5 = 0 give answers to 3 decimal places