Expand and simplify the expression (x+5)(x+8).

This question is about multiplying two brackets together. There are two parts to each bracket: x, +3 and x, +5. The parts in the first bracket must each be multiplied by both parts in the second bracket. We use the claw method for this. We will draw lines, that each represent a multiplication. Draw a line from the first x to the second x (see whiteboard diagram). This means x times x, which is x2  so we write x2 as the first part of our answer. Now draw a line from the first x, to the "+8". Every line means a mutliplication so this means +8 times x, which we write as +8x next to our x2. Now we draw two lines from the +5 to the parts in the second bracket (as shown in diagram, you can see why it is called the claw method now!). The first is +5 times x, so +5x, followed by +5 times +8, which is +40.  Now we have all parts to our answer: x2 +8x +5x +40. However we are not quite finished! We must simplify the expression, so write it with less parts to it! We can only simplify bits that look similar. So here the +8x and +5x are both numbers with an x attached to them. +8x means we have 8 x's and +5x means we have 5 x's. 8 + 5 = 13, so in total we have 13 x's, which we can write as +13x. So if we put this in our final answer, we get: x2 +13x +40. This is the correct answer.

JC

Related Maths GCSE answers

All answers ▸

Solve 5x - 2 > 3x + 11


Nicky buys a blender. 20% VAT is added to the price of the blender so Nicky has to pay £180. What is the price of the blender with no VAT added?


Find the mean, median, mode and range of this data: 2, 5,6,12,5


A right-angled triangle has one angle size 60 degrees, and hypotenuse of length 32cm. Calculate the length of the side opposite the 60 degree angle, to 3sf.