Algebra question

11 Plus Maths – Preparation and Information

Moderators: Section Moderators, Forum Moderators

Post Reply
11 Plus Mocks - Practise the real exam experience - Book Now
enema
Posts: 180
Joined: Fri Jan 31, 2014 1:45 pm

Algebra question

Post by enema »

Could I ask how others would answer this question:

"In 5 years time, John's dog will be x years old. How old was his dog 6 years ago?"

Do you work backwards from in 5 years time, ie x = (-5)+(-6) i.e. x = -11

Am I barking up completely the wrong tree, it seems particularly hard for 10 year olds?
yoyo123
Posts: 8099
Joined: Mon Jun 18, 2007 3:32 pm
Location: East Kent

Re: Algebra question

Post by yoyo123 »

I always find diagrams really useful with this sort of question
moved
Posts: 3826
Joined: Fri Oct 12, 2007 1:42 pm
Location: Chelmsford and pleased

Re: Algebra question

Post by moved »

Totally agree with Yoyo.

Draw a line with now in approx the middle, then put on the other info at the ends, enabling DC to see the 11.
equilibro
Posts: 109
Joined: Wed Sep 17, 2014 8:07 pm

Re: Algebra question

Post by equilibro »

[quote="enema" Do you work backwards from in 5 years time, ie x = (-5)+(-6) i.e. x = -11 ..... Am I barking up completely the wrong tree .....?[/quote] Right tree but wrong direction. In fact, "x" is as stated in the question i.e. now plus 5 not "-11". The age of the dog 6 years ago was x-11.
russet
Posts: 243
Joined: Sat Aug 10, 2013 12:46 pm

Re: Algebra question

Post by russet »

I agree with equilibro.

The question is not asking for an equation (with an = sign), but for an expression in terms of x. So, six years ago the age was x-11. If you are then given more information such as "the dog was two 5 years ago," you can then put this into an equation to find x.
enema
Posts: 180
Joined: Fri Jan 31, 2014 1:45 pm

Re: Algebra question

Post by enema »

Thank you for all the replies, they are very appreciated, especially as each post has broken down the answer even further :)
Post Reply