Algebraic Equations
Moderators: Section Moderators, Forum Moderators
Algebraic Equations
Hi, as I'm working through some of the Letts CEM practice material, we've come across this equation:
4b - 7 = 2b + 15
I'm not a teacher or a tutor, just a mum trying to help lol. I've tried to look up explanations of this sort and I'm struggling to find something clear enough for my daughter to understand. She's done basic algebra in class e.g. a+3=7 but this is somewhat out of my depth. Can I just ask if there are likely to be questions like this in the actual 11+? If I can't get her to understand how to do this, my simple answer will be to just move on as soon as you see it; don't waste time on it!
Your thoughts would be appreciated, thank you.
4b - 7 = 2b + 15
I'm not a teacher or a tutor, just a mum trying to help lol. I've tried to look up explanations of this sort and I'm struggling to find something clear enough for my daughter to understand. She's done basic algebra in class e.g. a+3=7 but this is somewhat out of my depth. Can I just ask if there are likely to be questions like this in the actual 11+? If I can't get her to understand how to do this, my simple answer will be to just move on as soon as you see it; don't waste time on it!
Your thoughts would be appreciated, thank you.
Re: Algebraic Equations
There should not any questions like this be as this is NOT in the new[ish) Primary curriculum.
I'd prefer you to ignore the question but if you want to know how this would be taught:
4b - 7 = 2b + 15
Using the balancing approach - which side has fewer b? [the right hand side] how many does it have? [2b]
We want to now subtract 2b from both sides [so the unknown is only on one side]
4b - 7 - 2b = 2b + 15 - 2b
2b - 7 = 15 now we need to look at the numbers and add 7 to both sides so we only has the unknown on its owm on the left.
2b - 7 + 7 = 15 + 7
2b = 22 now we know what 2b is we need to divide both sides by 2
2b/2 = 22/2
b = 11 now check by substituting back
4b - 7 = 44 - 7 = 37
2b + 15 = 22 + 15 = 37 so the solution [ie the ONLY number for which the equation is true] is b = 11
I'd prefer you to ignore the question but if you want to know how this would be taught:
4b - 7 = 2b + 15
Using the balancing approach - which side has fewer b? [the right hand side] how many does it have? [2b]
We want to now subtract 2b from both sides [so the unknown is only on one side]
4b - 7 - 2b = 2b + 15 - 2b
2b - 7 = 15 now we need to look at the numbers and add 7 to both sides so we only has the unknown on its owm on the left.
2b - 7 + 7 = 15 + 7
2b = 22 now we know what 2b is we need to divide both sides by 2
2b/2 = 22/2
b = 11 now check by substituting back
4b - 7 = 44 - 7 = 37
2b + 15 = 22 + 15 = 37 so the solution [ie the ONLY number for which the equation is true] is b = 11
Re: Algebraic Equations
Thank you, thank you, thank you!! I had seen the answer and the workings in the book (plus many similar questions on you tube videos and google) but could not quite grasp it. I do now so thank you and I do hope this type of question is not in the 11+!