prove that√7 is a irational
Answers
answer
step by step
since √7 =rational so
√7 =p/q and q not equal to 0
so√7/1 =p/q
hence proved
√7 =p/q
our contradiction is wrong so √7 =not (p/q)
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let us assume that √7 is a rational
√7=a/b,where a,b are coprimes and b is not equals to 0
squaring on both side
√7²=a²/b²
7=a²/b²
b²7=a²
b²=a²/7 ----------equaltion 1
(if p divides a² then p divides a) similarly here from equation 1,if 7 divides a² then 7 divides a
let a/7=k
a=7k in equation 1
b²= (7k)²/7
b²=49k²/7
b²=7k²
k²=b²/7----------equation 2
here from equation 2,if 7 divides b² then 7 divides b
from equation 1 and 2,7 divides both a² and b²,but here a,b are so primes
so our assumption is wrong
therefore √7 is an irrational number
this is the exact answer,hope this is helpful