Simplify (7+sqrt(5))/(sqrt(5)-1), leaving the answer in the form a+b*sqrt(5)

Step 1 - Identify the difference between the required form of the answer and the expression to be simplified: 

It can be seen that in order to simplify the expression we need to somehow get rid of the denominator.

Step 2 - Attempt a method to get rid of the denominator: 

The best way to get rid of the denominator is to multiply it by (sqrt(5)+1). In order to keep the expression the same we must do the same to the numerator as well. 

This gives us,

((7+sqrt(5))/(sqrt(5)-1))*((sqrt(5)+1)/(sqrt(5)+1))

Step 3 - Carry out the necessary calculations:

The top parts of the fractions multiply together and the bottom parts of the fractions multiply together.

For the top part this gives us,

(7+sqrt(5))(sqrt(5)+1) = 7sqrt(5)+7+5+sqrt(5)

= 8*sqrt(5)+12

For the bottom part this gives us,

(sqrt(5)-1)*(sqrt(5)+1) = 5+sqrt(5)-sqrt(5)-1 = 4

Dividing the top part by the bottom part gives us,

2*sqrt(5)+3

Step 4 - Check that the answer is in the correct form.

The question asks for an answer in the form,

a+b*sqrt(5)

Our answer can be written in this format with a = 3 and b = 2.

IR

Related Maths A Level answers

All answers ▸

A curve has the equation: x^4 + 2x -xy - y^3 - 10=0. Find dy/dx in terms of x and y.


Show that r^2(r + 1)^2 - r^2(r - 1)^2 ≡ 4r^3.


Find dy/dx for (x^2)(y^3) + ln(x^y) = 5sin(6x)/x^(1/2)


How do you divide polynomials? How do you do it with remainder?