Question Details

The set of all real values of x for which  ( x 2 | x + 9 | + x ) > 0 , is

Options

A

( , 3 ) ( 3 , )

B

( , 9 ) ( 3 , )

C

( 9 , 3 ) ( 3 , )

D

( , 9 ) ( 9 , )

Show Answer

Correct Answer :

Option A

( , 3 ) ( 3 , )

Solution :

To find the set of all real values of x for which the given inequality holds, let us write the given expression:

x2|x+9|+x>0


We can solve this inequality by considering two cases based on the definition of the absolute value function |x+9|.

Case 1: When x+90 (i.e., x9)

In this region, |x+9|=x+9.

Substituting this into the inequality, we get:

x2(x+9)+x>0

x2x9+x>0

x29>0

Factoring the left-hand side gives:

(x3)(x+3)>0

The solution to this quadratic inequality is:

x<3 or x>3

Taking the intersection with the case condition x9:

x[9,3)(3,)


Case 2: When x+9<0 (i.e., x<9)

In this region, |x+9|=(x+9).

Substituting this into the inequality, we get:

x2[(x+9)]+x>0

x2+x+9+x>0

x2+2x+9>0

Let us check the discriminant D of the quadratic expression x2+2x+9:

D=b24ac=224(1)(9)=436=32<0

Since the coefficient of x2 is positive (1>0) and the discriminant is negative, the quadratic expression x2+2x+9 is strictly positive for all real values of x.

Thus, all values of x in this case satisfy the inequality.

Taking the intersection with the case condition x<9:

x(,9)


Combining the solutions from both cases:

Taking the union of the solutions from Case 1 and Case 2:

x(,9)[9,3)(3,)

Combining (,9) and [9,3) gives:

x(,3)(3,)


Therefore, the set of all real values of x satisfying the inequality is (,3)(3,).

Unlock Our Free Library

Access expert-curated educational resources and study materials—completely free.

Discover more resources

You may also like

Mock Tests

View All
  • CTET
  • intermediate
  • No time limit
  • child development and pedagogy, mathematics, social science

  • SSC
  • intermediate
  • 2 hours and 30 mins
  • child development and pedagogy, mathematics, social science

Ask AI Tutor
5 left
Q1 View Question & Options
AI Tutor is solving this question...
Reading question context & options...