Question

x² – 4x = 0, x = 0, –2, 4

Answer 1

Given: x² – 4x = 0 and x = 0, –2 and 4.
we have to determine if the given values of x satisfy the quadratic equation
On substituting x = 0 in L.H.S. of the given equation, we get;
(0)² – 4(0)
= 0 – 0
= 0
=> L.H.S. = R.H.S.
Thus, x = 0 satisfies the given equation.
Therefore, x = 0 is a root of the given quadratic equation.

On substituting x = –2 in L.H.S. of the given equation, we get:
(–2)² – 4(–2)
= 4 + 8
= 12
= > L.H.S. $\ne$ R.H.S.
Thus, x = –2 does not satisfy the given equation.
Therefore, x = –2 is not a root of the given quadratic equation.

On substituting x = 4 in L.H.S. of the given equation, we get:
(4)² – 4(4)
= 16 – 16
= 0
=> L.H.S. = R.H.S.
Thus, x = 4 satisfies the given equation.
Therefore, x = 4 is a root of the given quadratic equation.