Mathematics
Grade-8
Easy

Question

What should come in place of both x in the equation:
fraction numerator x over denominator square root of 128 end fraction equals fraction numerator square root of 162 over denominator x end fraction

  1. 12
  2. 14
  3. 144
  4. 196

hintHint:

In this question we have given the expression with an unknown value x. Here the concept of square roots can be used. A number's square root is a value that, when multiplied by itself, yields the original number. The other way to square an integer is to find its square root.
For example:
square root of 4 equals space square root of 2 cross times 2 end root
square root of 4 equals space 2

The correct answer is: 12


    The expression here is given as:
    Let fraction numerator x over denominator square root of 128 end fraction equals fraction numerator square root of 162 over denominator x end fraction
N o w space w e space w i l l space c r o s s space m u l t i p l y space t h e space t e r m s space a n d space p r o c e e d space f u r t h e r colon
x squared equals square root of 128 cross times square root of 162
N o w space m u l t i p l y i n g space t h e space r o o t s space t e r m comma space w e space g e t colon
x squared equals square root of 128 cross times 162 end root
x squared equals square root of 20736
N o w space f a c t o r i sin g space 20736 comma space w e space g e t colon
x squared equals square root of 2 space cross times space 2 space cross times space 2 space cross times space 2 space cross times space 2 space cross times space 2 space cross times space 2 space cross times space 2 space cross times space 3 space cross times space 3 space cross times space 3 space cross times space 3 space end root
C o m b i n i n g space i t space i n space p a i r s space w e space g e t colon
x squared equals square root of 64 cross times 2 cross times 18 cross times 9 end root
x squared equals square root of 8 squared cross times 6 squared cross times 3 squared end root
x squared equals 8 cross times 6 cross times 3
x squared equals 144 space
N o w space w e space h a v e space g o t space t h e space v a l u e space o f space x squared comma space s o space t a k i n g space s q u a r e space r o o t s space o n space b o t h space s i d e s comma space w e space g e t colon
square root of x squared end root equals square root of 144
x equals square root of 144
x equals square root of 12 cross times 12 end root
x equals 12
    So the value of x is 12.

    In this question, we have given the expression with two values with square root and we have to find the value of x. We used the cross multiplication technique to solve this expression. After cross multiplying we used the square root method to find the value of x which came out to be 12.

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