Question

prove that 7 is a irrational no​

Answer 1

Step-by-step explanation:

Let us assume that √7 be rational.

then it must in the form of p / q [q ≠ 0] [p and q are co-prime]

√7 = p / q

=> √7 x q = p

squaring on both sides

=> 7q2= p2 ------ (1)

p2 is divisible by 7

p is divisible by 7

p = 7c [c is a positive integer] [squaring on both sides ]

p2 = 49 c2 --------- (2)

Subsitute p2 in equ (1) we get

7q2 = 49 c2

q2 = 7c2

=> q is divisible by 7

thus q and p have a common factor 7.

there is a contradiction

as our assumsion p & q are co prime but it has a common factor.

So that √7 is an irrational.