show that √3 + √5 rational √p + √q irrational √1 where √2 is irrational
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Step-by-step explanation:
To prove : √3+√5 is irrational.
Let us assume it to be a rational number.
Rational numbers are the ones that can be expressed in q/pform where p,q are integers and q isn't equal to zero.
√3 +√5= q/p
√3=q/p−√5
squaring on both sides,
3= q²/p²−2.√5 (q/p )+5
⇒ (2√5p)/q =5−3+(p2/q2)
⇒(2√5p)/q=2q²-p²/q²
⇒√5=2q²-p²/q²×q/2p
⇒√5=(2q²-p²)/2pq
As p and q are integers RHS is also rational.
As RHS is rational LHS is also rational i.e √5 is rational.
But this contradicts the fact that √5 is irrational.
This contradiction arose because of our false assumption.
so, √3 +√5 irrational.
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