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Answers
Any value whether Positive or Negative inside Modulus function becomes Positive. That is IxI = x and I-xI = x
⇒ the value inside the modulus can be positive or negative but it finally becomes positive
⇒ here the expression inside the modulus is (x - 1)
from the definition of modulus function the expression (x - 1) can be positive or negative.
let us consider the case when (x - 1) is positive
⇒ the given equation becomes : x² + x - 1 = 1
⇒ x² + x - 2 = 0
⇒ x² + 2x -x - 2 = 0
⇒ x = - 2 or x = 1
now let us consider the case when (x - 1) is negative
⇒ the given equation becomes x² -(x - 1) = 1
⇒ x² - x + 1 = 1
⇒ x² - x = 0
⇒ x(x - 1) = 0
⇒ x = 0 or x = 1
so the possible solutions of the equation x² + Ix - 1I = 1 are :
x = -2 (or) x = 0 (or) x = 1
these are possible solutions but not actual solutions which satisfy the equation.
let us verify whether they are actually satisfying the equation or not
substituting x = -2 in the given question we get :
⇒ (-2)² + I-2 - 1I = 1
we know that anything inside modulus function finally becomes positive
⇒ 4 + 3 = 1
⇒ 7 = 1 but we know that 7 cannot be equal to 1
so -2 is not the solution the given question.
substituting x = 0 in the equation we get :
⇒ 0 + I-1I = 1
we know that I-1I = 1
⇒ 1 = 1
so the solution x = 0 is an actual solution to the given question.
substituting x = 1 in the equation we get :
⇒ 1² + 0 = 1
⇒ 1 = 1
so the solution x = 1 is an actual solution to the given question.
⇒ the number of solutions of x² + Ix - 1I = 1 are 2 and they are 0 and 1