Mathematics for IGCSE & O level - Surds (Section 2 - No. 20)

If x = √6 - √5, what is the value of x^2 + 2√30?

11 - 2√30

11+2√30

x^2 = (√6 - √5)^2 = 6 - 2√30 + 5. Therefore, x^2 + 2√30 = 6 - 2√30 + 5 + 2√30 = 11