prove that √7 is an irrational
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Let us assume that √7 can be expressed in the form p/q where q is not equal to
zero.
And p and q has no common factor other than 1.
So,√7=p/q
Square both sides we got
7=p^2/q^2
7q^2=p^2...(1)
So, 7 divide p
reasons:if a no. say X can divide no.say
say y^2 then X can divide y
so, let 7m=p
squaring both sides we got
49m^2=p^2
replacing the p^2 in equation 1 we got
7q^2=49m^2
q^2=7m^2
so, 7 divide q
Now since 7 is the factor of both p and q
Hence this contradict the fact that √7 is a rational no.
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Answer:
Step-by-step explanation:
Lets assume that √7 is rational number. ie √7=p/q.
suppose p/q have common factor then
we divide by the common factor to get √7 = a/b were a and b are co-prime number.
that is a and b have no common factor.
√7 =a/b co- prime number
√7= a/b
a=√7b
squaring
a²=7b² .......1
a² is divisible by 7
a=7c
substituting values in 1
(7c)²=7b²
49c²=7b²
7c²=b²
b²=7c²
b² is divisible by 7
that is a and b have atleast one common factor 7. This is contridite to the fact that a and b have no common factor.This is happen because of our wrong assumption.
√7 is irrational✔✔
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