Expand and simplify 4(x+5) + 3(x-7)

When we're doing algebra and expanding brackets, our first step is to multiply everything inside each bracket by what we have just before the bracket. Let's start with the 4(x+5). 4 lots of our unknown mystery number x would give us 4x. 4 lots of 5 gives us 20. So together we have 4x + 20. Doing the same for 3(x-7), 3 lots of x gives us 3x. 3 lots of -7 gives us -21. So all together we have 3x-21. Putting both parts together we have 4x + 20 + 3x - 21. Now we need to simplify this. If we write this in a different order with our x's together and our integers (or whole numbers) together we have 4x + 3x + 20 - 21. From here we can see we have 7x - 1. And there's our final answer.

CM

Related Maths GCSE answers

All answers ▸

Make c the subject of the formula a=3c-12


Solve the simultaneous equations: y = 4x^2 - 9x - 1 and y = 5 - 4x


Solve 3x^2 + 5x +2


Bob sprints down a 100 metre track as fast as he can and as he arrives at the finish, a light gate cuts a timer that has been active since Bob began his sprint. It reads 12.45 seconds. calculate Bobs average speed during the sprint.