spaceshowfeature1
New member
- Joined
- Jul 20, 2018
- Messages
- 47
I’m solving the inequality for x. Here it is: x^6+9x^5+13x^4>-7x^4.
I factor the equation into: x^4(x+5)(x+4)>0 This means that x=-5, x=-4, and x=0 at zero. Now I must put these values on a number line.
Ok, now that these values are on the number line, I pick the test points x=-6, x=-4.5,x=-3, and x=1. The first, third, and last test points satisfy the inequality. This is where the trouble begins.
I write my answers in interval notation as follows: (-infinity,-5) and (-4,infinity). The reason why I got. (-4, infinity) and not (-4,0) and (0,infinity) is because BOTH sections satisfy the inequality, so I combined them into the larger solution (-4,infinity) because both sections satisfy the inequality. I’ve been doing this type of thing and getting the right answer for as long as i’ve been doing these types of problems, but now I’m wrong.
What is is my mistake? Is Symbolab’s solution just wrong? What can I do in the future to fix this mistake?
Thanks for all the help.
I factor the equation into: x^4(x+5)(x+4)>0 This means that x=-5, x=-4, and x=0 at zero. Now I must put these values on a number line.
Ok, now that these values are on the number line, I pick the test points x=-6, x=-4.5,x=-3, and x=1. The first, third, and last test points satisfy the inequality. This is where the trouble begins.
I write my answers in interval notation as follows: (-infinity,-5) and (-4,infinity). The reason why I got. (-4, infinity) and not (-4,0) and (0,infinity) is because BOTH sections satisfy the inequality, so I combined them into the larger solution (-4,infinity) because both sections satisfy the inequality. I’ve been doing this type of thing and getting the right answer for as long as i’ve been doing these types of problems, but now I’m wrong.
What is is my mistake? Is Symbolab’s solution just wrong? What can I do in the future to fix this mistake?
Thanks for all the help.