x2−4x+7>x+3x2−5x+4>0(x−1)(x−4)>0Example 5: Let g(x)=ln(x2+x−5) and let h(x)=ln(x+4). What are all values of x for which g(x)<h(x) ?Domain: ln(x+4) term only defined whenx+4>0⇒x>−4g(x)<h(x)⇒g(x)−h(x)<0
Q. x2−4x+7>x+3x2−5x+4>0(x−1)(x−4)>0Example 5: Let g(x)=ln(x2+x−5) and let h(x)=ln(x+4). What are all values of x for which g(x)<h(x) ?Domain: ln(x+4) term only defined whenx+4>0⇒x>−4g(x)<h(x)⇒g(x)−h(x)<0
Expressing Inequality: First, let's express the inequality g(x)<h(x) in terms of the given functions.g(x)=ln(x2+x−5)h(x)=ln(x+4)So, we need to find the values of x for which ln(x2+x−5)<ln(x+4).
Comparison of Arguments: Since the natural logarithm function ln(x) is an increasing function, the inequality ln(a)<ln(b) holds if and only if a<b. Therefore, we can remove the logarithms and compare the arguments directly: x2+x−5<x+4
Solving Quadratic Inequality: Now, let's solve the inequality x2+x−5<x+4 by subtracting x and 4 from both sides:x2+x−x−5−4<x+4−x−4x2−9<0
Factoring and Testing Intervals: The inequality x2−9<0 can be factored as (x−3)(x+3)<0. We need to find the values of x where this product is negative.
Testing Interval (−∞,−3): To determine where the product (x−3)(x+3) is negative, we look at the intervals defined by the roots of the equation (x−3)(x+3)=0, which are x=3 and x=−3. We test intervals (−∞,−3), (−3,3), and (3,∞) to see where the product is negative.
Testing Interval (−3,3): Testing the interval (−∞,−3): Let's choose x=−4 (which is also in the domain of ln(x+4)). We have (−4−3)(−4+3)=(−7)(−1)=7, which is positive. So, the product is not negative in this interval.
Testing Interval 3,∞):</b>Testingtheinterval$3,∞):Let′schoose$x=0. We have 0−3)(0+3)=(−3)(3)=−9, which is negative. So, the product is negative in this interval.
Final Solution: Testing the interval (3,∞): Let's choose x=4. We have (4−3)(4+3)=(1)(7)=7, which is positive. So, the product is not negative in this interval.
Final Solution: Testing the interval (3,∞): Let's choose x=4. We have (4−3)(4+3)=(1)(7)=7, which is positive. So, the product is not negative in this interval.Therefore, the solution to the inequality (x−3)(x+3)<0 is the interval (−3,3). However, we must also consider the domain of the original inequality, which requires x>−4 due to the ln(x+4) term.
Final Solution: Testing the interval (3,∞): Let's choose x=4. We have (4−3)(4+3)=(1)(7)=7, which is positive. So, the product is not negative in this interval.Therefore, the solution to the inequality (x−3)(x+3)<0 is the interval (−3,3). However, we must also consider the domain of the original inequality, which requires x>−4 due to the ln(x+4) term.Combining the solution to the inequality with the domain restriction, we find that the values of x for which g(x)<h(x) are in the interval (−3,3), but x must also be greater than x=41. Since x=42 is greater than x=41, the domain restriction does not change our solution interval.
Final Solution: Testing the interval (3,∞): Let's choose x=4. We have (4−3)(4+3)=(1)(7)=7, which is positive. So, the product is not negative in this interval.Therefore, the solution to the inequality (x−3)(x+3)<0 is the interval (−3,3). However, we must also consider the domain of the original inequality, which requires x>−4 due to the ln(x+4) term.Combining the solution to the inequality with the domain restriction, we find that the values of x for which g(x)<h(x) are in the interval (−3,3), but x must also be greater than x=41. Since x=42 is greater than x=41, the domain restriction does not change our solution interval.The final answer is that the values of x for which x=45 is less than x=46 are all x in the interval (−3,3).
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