i) Simplify (2 * sqrt(7))^2 ii) Find the value of ((2 * sqrt(7))^2 + 8)/(3 + sqrt(7)) in the form m + n * sqrt(7) where n and m are integers.

i) (2sqrt(7))2 = 2 sqrt(7)2 = 4 * 7 = 28      (1 mark) ii) First of all substitute the answer from above.    ((2 * sqrt(7))2 + 8) / (3 + sqrt(7)) = (28 + 8) / (3 + sqrt(7)) = 36 / (3 + sqrt(7)) Multiply by (3 - sqrt(7))/(3 - sqrt(7)) = 1.    36 / (3 + sqrt(7)) = 36 / (3 + sqrt(7)) * (3 - sqrt(7)) / (3 - sqrt(7)) = (36 * (3 - sqrt(7))) / ((3 + sqrt(7)) * (3-sqrt(7)) = (108 - 36 * sqrt(7)) / (9 + 3 * sqrt(7) - 3 * sqrt(7) - 7) = (108 - 36 * sqrt(7)) / 2 = 54 - 18 * sqrt(7).      (3 marks) (Hence m=54 and n=-18) 

AB
Answered by Andrew B. Maths tutor

7339 Views

See similar Maths A Level tutors

Related Maths A Level answers

All answers ▸

How to expand squared brackets?


A radio sells for £63, after a 40% increase in the cost price. Find the cost price.


The radius of a circular disc is increasing at a constant rate of 0.003cm/s. Find the rate at which the area is increasing when the radius is 20cm.


(a) Express x +4x+7 in the form (x+ p) +q , where p and q are integers.


We're here to help

contact us iconContact ustelephone icon+44 (0) 203 773 6020
Facebook logoInstagram logoLinkedIn logo

MyTutor is part of the IXL family of brands:

© 2025 by IXL Learning