Question

Prove that 2-√5 is irration

Answer 1

Answer:

suppose 2-✓5 is rational

therefore 2-✓5=a/b where a and b are co prime

-✓5=a/b -2

-✓5=a-2b/b

since a and b are integers,

therefore a-2b/b is rational number

-✓5=a rational number

Which contradicts the fact that -✓5 is irrational

therefore our assumption is wrong

therefore 2-✓5 is irrational