Question #228837

Simplify (√5+1)÷(√5-1)


Expert's answer

Answer:


To solve this problem we should multiply both numerator and denominator by  (5+1)(5+1)\frac{(\sqrt{\smash[b]{5}}+1)}{(\sqrt{\smash[b]{5}}+1)} =1 (because multiplying any number by 1 doesn't change it) by itself to get a 'normal' number on the bottom. So in this case we do:


(5+1)(5−1)∗(5+1)(5+1)=(5∗5+5+5+1)(5∗5+5−5−1)=(5+25+1)(5−1)\frac{(\sqrt{\smash[b]{5}}+1)}{(\sqrt{\smash[b]{5}}-1)}*\frac{(\sqrt{\smash[b]{5}}+1)}{(\sqrt{\smash[b]{5}}+1)}=\frac{(\sqrt{\smash[b]{5}}*\sqrt{\smash[b]{5}}+\sqrt{\smash[b]{5}}+\sqrt{\smash[b]{5}}+1)}{(\sqrt{\smash[b]{5}}*\sqrt{\smash[b]{5}}+\sqrt{\smash[b]{5}}-\sqrt{\smash[b]{5}}-1)}=\frac{(5+2\sqrt{\smash[b]{5}}+1)}{(5-1)}


  ⟹  (5+25+1)(5−1)=(6+25)(4)=2(3+5)4=3+52\implies \frac{(5+2\sqrt{\smash[b]{5}}+1)}{(5-1)}=\frac{(6+2\sqrt{\smash[b]{5}})}{(4)}=\frac{2(3+\sqrt{\smash[b]{5}})}{4}=\frac{3+\sqrt{\smash[b]{5}}}{2}


Answer:

3+52\frac{3+\sqrt{\smash[b]{5}}}{2}



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