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) 

Answered by Andrew B. Maths tutor

6652 Views

See similar Maths A Level tutors

Related Maths A Level answers

All answers ▸

The curve C has the equation (x^2)+4xy-8(y^2)+27=0. Find dy/dx in terms of x and y.


A curve is defined by parametric equations: x = t^(2) + 2, and y = t(4-t^(2)). Find dy/dx in terms of t, hence, define the gradient of the curve at the point where t = 2.


Calculate (7-i*sqrt(6))*(13+i*sqrt(6))


What is the quotient rule and how is it applied?


We're here to help

contact us iconContact usWhatsapp logoMessage us on Whatsapptelephone icon+44 (0) 203 773 6020
Facebook logoInstagram logoLinkedIn logo
Cookie Preferences