Question

Question 15

Which of the following equations cannot be formed using the equation x = 7

(a) 2x + 1 = 15
(b) 7x - 1 = 50
(c) x - 3 = 4
(d) $\frac{x}{7}-1=0$

Answer 1

We have, x = 7
Put x=7 in all the equations and equation which doesnt satisfy x=7 can not be formed by taking x=7

(a) 2x+1=15
put x=7
$2\times 7$+1=15
15=15
So x=7 is a solution of option (a)

(b) 7x-1=50
Put x=7
$7\times 7$-1=50
48=50 (Which is not true)
So, x=7 does not satisfy equation (b)
hence Equation given in option (b) can not be formed by taking x=7
So our answer is option (b)

Similarly we can check for options (c) and (d) by putting x=7
but they will satisfy the condition given.