Solve the polynomial function
Favorites|Homepage
Subscriptions | sitemap
HOME > > Solve the polynomial function

Solve the polynomial function

[From: ] [author: ] [Date: 12-04-23] [Hit: ]
x = 5 or x = -3.now we unpretend we have an equation.we put -3 and 5 on a number line, and we test a number less than -3, between -3 and 5, and more than 5 to see whether or not the number is positive or negative.......
and graph the solution set on a number line. express the solution set in interval notation

x2 - 2x - 15 < 0

can anyone please help and explain this to me? i keep getting the wrong answer and its quite frustrating. please help! i would appreciate it soooo much!

-
what you do is pretend that we have an equation.

solve:

x^2 - 2x - 15 = 0

factor:

(x - 5) (x + 3)= 0

x = 5 or x = -3.

now we unpretend we have an equation.

we put -3 and 5 on a number line, and we test a number less than -3, between -3 and 5, and more than 5 to see whether or not the number is positive or negative. we are looking for when it's less than 0.

----+..............-...............+--…
........-3..................5.........…

-4 is less than -3. lets plug x=-4 into the inequality.

(-4)^2 - 2 (-4) - 15 = 16 + 8 - 15 = 9 which is positive, so this is not right

0 is in between -3 and 5. lets check x=0

0^2 - 2(0) - 15 = -15. this is less than 0

6 is more than 5. lets check it.

6^2 - 2(6) - 15 = 36 - 12 - 15 = 9 . this is more than 0.

the solution for x2 - 2x - 15 < 0 is -3 < x < 5.

-
Sorry, this line editor does not accept graphs

x² – 2x – 15 < 0

First solve x² – 2x – 15 = 0, that is (x – 5)(x + 3) = 0, the solutions are x = 5 or x = -3

Since the graph of this polynomial is a parabola that opens up (I know the pattern, do you?) and the roots are -3 and 5, the domain [-3, 5] are values of x such that the polynomial is either on the x-axis or below the y-axis.

Therefore, the solution to your inequality is x in the open interval (-3, 5)
If you wish -3 < x < 5.

-
(x-5) (x+3) < 0

(x-5) < 0
add 5 to 0

x<5

(x+3) <0
subtract 3

x<-3

x< 5 or -3
1
keywords: function,the,polynomial,Solve,Solve the polynomial function
New
Hot
© 2008-2010 http://www.science-mathematics.com . Program by zplan cms. Theme by wukong .