Precalc0011to0016-page3

# Precalc0011to0016-page3 - to solve TIP 2 To avoid sign...

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(Section 0.11: Solving Equations) 0.11.3 Example 2 (Using the Quadratic Formula) Solve the equation 2 x 2 ± 7 x = 15 using the Quadratic Formula. § Solution WARNING 4 : We must rewrite the equation in general form before we apply the Quadratic Formula. We must isolate 0 on one side of the equation. (Sometimes, it is easier to isolate 0 on the left-hand side, which is permissible.) 2 x 2 ± 7 x = 15 2 x 2 ± 7 x ± 15 = 0 TIP 1 : If we had been asked to solve 4 x 2 ± 14 x ± 30 = 0 , we could divide both sides by 2 and obtain the equation above, which is easier
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Unformatted text preview: to solve. TIP 2 : To avoid sign errors, we will identify a , b , and c before we apply the Quadratic Formula. Here, a = 2 , b = ± 7 , and c = ± 15 . x = ± b ± b 2 ± 4 ac 2 a = ± ± 7 ( ) ± ± 7 ( ) 2 ± 4 2 ( ) ± 15 ( ) 2 2 ( ) = 7 ± 49 + 120 4 = 7 ± 169 4 WARNING 5 : We must simplify the radical . (If we had obtained, say, 7 ± 2 4 , there would be no need to simplify.) = 7 ± 13 4...
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