prove that 4+3√ 5 is an irrational number
Answers
Step-by-step explanation:
Let us assume that 4+3√5 is a rational number.
4+3√5=a/b [ Here a and b are co prime]
3√5=a/b-4
√5=a-4b/3b
Since, a,b,4b,3b are integers.
a-4b/3b is a rational number and √5 is an irrational number.
So, 4+3√5 is an irrational number....
Proved!!!!
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CONCEPT:
rational and irrational numbers: rational numbers can be written in the form of fraction(a/b) and irrational numbers cannot be written in the form of fractions.
Here to prove 4+3√5 is an irrational number we use the method of contradiction.
Contradiction method is a method in which we assume the opposite to the statement and proves that the opposite of statement is wrong thereby proving that the original statement is right
GIVEN:
a statement is given
4+3√5 is an irrational number
FIND:
we want to prove that 4+3√5 is an irrational number.
SOLUTION:
let the statement be P:4+3√5 is an irrational number.
let us assume a CONTRADICTION to the given statement and check it's validity
CONTRADICTION IS 4+3√5 is rational.
let's check it's validity
if 4+3√5 is rational we can write it in fractional form
so 4+3√5 =a/b
3√5=a/b-4
3√5=(a-4b)/b
√5=(a-4b)/3b
in the RHS a,b,4,3 are integers.
so (a-4b)/3b is rational
in LHS it's √5.
we know that SQUARE ROOT OF ANY INTEGERS IS IRRATIONAL.
so here it comes the situation that irrational =rational
so the contradiction 4+3√5 is rational is wrong
so the number 4+3√5 is irrational and hence proved
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