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19 f(x)=x^2-4 g(x)=2x+1 Solve fg(x)gt 0 Sho w c wor king.

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19
f(x)=x^2-4
g(x)=2x+1
Solve fg(x)gt 0
Sho w c wor king.

19 f(x)=x^2-4 g(x)=2x+1 Solve fg(x)gt 0 Sho w c wor king.

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SeymourElite · Tutor for 8 years

Answer

To solve this inequality, first calculate fg(x) by multiplying function f(x) and g(x):<br /><br />fg(x)=f(x) * g(x)=(x^2 - 4)(2x+1)=2x^3+x^2-8x-4 > 0 <br /><br />Setting this equal to zero gives the roots of the equation<br /><br />2x^3 + x^2 - 8x - 4 = 0<br /><br />Since this equation is not easy to solve for by hand, we can determine the roots numerically and approximately find them to be: <br />x ~ -2.101, -0.6438, and 1.7446<br /><br />To summarize:<br />1. If x < -2.101 then 2x^3 + x^2 - 8x - 4 > 0<br />2. If -2.101 < x < -0.6438 then 2x^3 + x^2 - 8x - 4 < 0<br />3. If -0.6438 < x < 1.7446, then 2x^3 + x^2 - 8x - 4 > 0<br />4. If 1.7446 < x then 2x^3 + x^2 - 8x - 4 < 0<br /><br />This makes the solution to the given inequality as: x ∈ (-∞, -2.101) ∪ (-0.6438, 1.7446)
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