Solve and Interval Notation: 1 < 4x + 3 < 9

Quadratic equations and inequalities, variation equations, function notation, systems of equations, etc.
Tiger
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Solve and Interval Notation: 1 < 4x + 3 < 9

Postby Tiger » Tue Mar 03, 2009 12:04 am

Can anyone help me understand this problem? I need to solve and apply interval notation.

1 < 4x + 3 < 9

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stapel_eliz
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Postby stapel_eliz » Tue Mar 03, 2009 1:29 pm

Tiger wrote:Can anyone help me understand this problem? I need to solve and apply interval notation.

1 < 4x + 3 < 9

How would you solve "4x + 3 = 9"? How about solving "1 = 4x + 3"? You use much the same methods for solving linear inequalities, even when they have three "halves", as yours does. :wink:

For instance:

. . . . .-2 < 3x + 4 < 13

. . . . .-2 - 4 < 3x + 4 - 4 < 13 - 4

. . . . .-6 < 3x < 9

. . . . .(-6)/3 < (3x)/3 < 9/3

. . . . .-2 < x < 3

The "interval notation" presentation of the above solution would be "(-2, 3)". Follow the same pattern with your exercise. :D


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