Math  /  Algebra

Question[/2[-/ 2 Points] DETAILS MY NOTES SALGTRIG4 1.7.044.MI.
Solve the nonlinear inequality. Express the solution using interval notation. x2+2x>3x^{2}+2 x>3

Studdy Solution

STEP 1

Assumptions
1. We need to solve the inequality x2+2x>3x^2 + 2x > 3.
2. We will express the solution in interval notation.
3. We will assume xx is a real number.

STEP 2

First, let's rewrite the inequality in standard form by moving all terms to one side of the inequality.
x2+2x3>0x^2 + 2x - 3 > 0

STEP 3

Next, we need to factor the quadratic expression x2+2x3x^2 + 2x - 3. To do this, we look for two numbers that multiply to 3-3 and add to 22.

STEP 4

The factors of 3-3 that add up to 22 are 33 and 1-1. Therefore, we can factor the quadratic expression as:
(x+3)(x1)>0(x + 3)(x - 1) > 0

STEP 5

To solve the inequality (x+3)(x1)>0(x + 3)(x - 1) > 0, we need to determine the intervals where the product of the factors is positive. We do this by finding the critical points where each factor is zero.
x+3=0x=3x + 3 = 0 \quad \Rightarrow \quad x = -3 x1=0x=1x - 1 = 0 \quad \Rightarrow \quad x = 1

STEP 6

The critical points divide the real number line into three intervals: (,3)(-\infty, -3), (3,1)(-3, 1), and (1,)(1, \infty). We need to test a point in each interval to determine where the inequality holds.

STEP 7

Choose a test point in the interval (,3)(-\infty, -3), for example, x=4x = -4.
(x+3)(x1)=(4+3)(41)=(1)(5)=5>0(x + 3)(x - 1) = (-4 + 3)(-4 - 1) = (-1)(-5) = 5 > 0
Since the product is positive, the inequality holds in the interval (,3)(-\infty, -3).

STEP 8

Choose a test point in the interval (3,1)(-3, 1), for example, x=0x = 0.
(x+3)(x1)=(0+3)(01)=3(1)=3<0(x + 3)(x - 1) = (0 + 3)(0 - 1) = 3(-1) = -3 < 0
Since the product is negative, the inequality does not hold in the interval (3,1)(-3, 1).

STEP 9

Choose a test point in the interval (1,)(1, \infty), for example, x=2x = 2.
(x+3)(x1)=(2+3)(21)=5(1)=5>0(x + 3)(x - 1) = (2 + 3)(2 - 1) = 5(1) = 5 > 0
Since the product is positive, the inequality holds in the interval (1,)(1, \infty).

STEP 10

Combine the intervals where the inequality holds. The solution to the inequality is the union of the intervals (,3)(-\infty, -3) and (1,)(1, \infty).

STEP 11

Express the solution in interval notation.
(,3)(1,)(-\infty, -3) \cup (1, \infty)
The solution to the inequality x2+2x>3x^2 + 2x > 3 in interval notation is (,3)(1,)(-\infty, -3) \cup (1, \infty).

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