Question

If x= 7y+3 and z= 49y^2 then what is 'z' in term of x?
A) 4
B) 3
C) 2
D) 6

Answer 1

Heya !!

X = 7Y + 3

7Y = ( X - 3 )

Y = ( X - 3 / 7 )

And,

Z = 49Y²

Z = 49 × ( X - 3/7)²

=> 49 × ( X - 3 )² / (7)²

=> 49 × ( X - 3 )² / 49

=> ( X - 3 )²

=> ( X )² + (3)² - 2 × X × 3

=> X² + 9 - 6X

=> X² - 6X + 9

=> X² - 3X - 3X + 9

=> X ( X - 3 ) - 3 ( X - 3 )

=> ( X - 3 ) ( X - 3 ) = 0

=> ( X - 3 ) = 0

=> X = 3

Hence,

Option ( C ) is the correct answer.