Math, asked by princeraj83410, 10 months ago

prove that 2root3 plus root 5 is irrational​

Answers

Answered by risky46
0

Answer:

To Prove :  2√3 + √5 is irrational

we know that √3 & √5 are irrational numbers.

Now we use result which states that

Product of a rational and an irrational no. is an irrational no.

⇒ 2√3 is irrational no.

Now. according to closure property of irrational no.

Sum of two irrational no. is also an irrational no.

⇒ 2√3 + √5 is an irrational no.

Step-by-step explanation:

Your Answer

BRAINLIST

Answered by Anonymous
5

Answer:

To Prove

2 \sqrt{3}  +  \sqrt{5}

as irrational.

Proof

let \: 2 \sqrt{3}  +  \sqrt{5}  \: is \: a \: rational \: number \\  2 \sqrt{3}  +  \sqrt{5} =  \frac{p}{q} (where \: p \: and \: q \: are \: co - prime \: and \: q \: is \: not \: \\  equal \: to \: zero) \\

squaring both sides

 {(2 \sqrt{3} +  \sqrt{5})  }^{2}  =  { (\frac{p}{q} )}^{2}   \\ \\ 12 + 5 + 4 \sqrt{15}  =  \frac{ {p}^{2} }{ {q}^{2} }  \\  \\ 17 + 4 \sqrt{15}  =  \frac{ {p}^{2} }{ {q}^{2} }  \\  \\ 4 \sqrt{15}  = \frac{ {p}^{2} }{ {q}^{2} }  - 17 \\  \\ 4 \sqrt{15}   =  \frac{ {p}^{2}  - 17 {q}^{2} }{ {q}^{2} }  \\  \\  \sqrt{15}  = \frac{ {p}^{2}  - 17 {q}^{2} }{ 4{q}^{2} }

  • Here LHS is product of two irrational numbers is also irrational whereas RHS is a rational number.
  • This is not possible.
  • Our assumption is wrong.
  • Therefore, it is an irrational number.

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