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Factoring Quadratic Trinomials. …beyond the guess and test method. Topics. 1. Standard Form 2. When c is positive and b is positive 3. When c is positive and b is negative 4. When c is negative 5. When the trinomial is not factorable 6. When a does not equal 1
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Factoring Quadratic Trinomials …beyond the guess and test method.
Topics 1. Standard Form 2. When c is positive and b is positive 3. When c is positive and b is negative 4. When c is negative 5. When the trinomial is not factorable 6. When a does not equal 1 7. When there is a GCF
Standard Form The standard form of any quadratic trinomial is a=3 b=-4 c=1
Now you try. a = ?? b = ?? c = ?? Click here when you are ready to check your answers!
Recall The standard form of any quadratic trinomial is a = 2 b = -1 c = 5 Try Another!
a = ?? b = ?? c = ?? Go on to factoring!
Factoring when a=1 and c > 0. First list all the factors of c. 1 12 2 6 3 4
Find the pair that adds to ‘b’ 1 12 2 6 3 4 These numbers are used in the factored expression.
Now you try. 1. 2. 3. Click here when you are ready to check your answers!
Recall 1 24 2 12 3 8 4 6 We need to list the factors of c. So we get: Try some others!
(x+3)(x+3) (x+2)(x+3) (x+1)(x+6) (x+2)(x+3) Go on to factoring where b is negative!
Factoring when c >0 and b < 0. Since a negative number times a negative number produces a positive answer, we can use the same method. Just remember to use negatives in the expression!
Let’s look at First list the factors of 12 1 12 2 6 3 4 We need a sum of -13 Make sure both values are negative!
Now you try. 1. 2. 3. Click here when you are ready to check your answers!
Recall In this case, one factor should be positive and the other negative. 1 8 2 4 We need a sum of -6 Try some others!
(x-3)(x-4) (x-3)(x+4) (x-2)(x-2) (x-1)(x-4) Go on to factoring where c is negative!
Factoring when c < 0. We still look for the factors of c. However, in this case, one factor should be positive and the other negative. Remember that the only way we can multiply two numbers and come up with a negative answer, is if one is number is positive and the other is negative!
Let’s look at In this case, one factor should be positive and the other negative. 1 12 2 6 3 4 We need a sum of -1
Now you try. 1. 2. 3. 4. Click here when you are ready to check your answers!
Recall In this case, one factor should be positive and the other negative. 1 18 2 12 3 6 We need a sum of 3 Try some others!
(x-3)(x+5) (x+3)(x-5) (x-5)(x+6) (x-6)(x-5) Go on to trinomials that are not factorable
Prime Trinomials Sometimes you will find a quadratic trinomial that is not factorable. You will know this when you cannot get b from the list of factors. When you encounter this write not factorable or prime.
Here is an example… 1 18 2 9 3 6 Since none of the pairs adds to 3, this trinomial is prime.
Now you try. factorable prime factorable prime factorable prime Go on to factoring when a≠1
When a ≠ 1. Instead of finding the factors of c: Multiply a times c. Then find the factors of this product. 1 70 2 35 5 14 7 10
We still determine the factors that add to b. 1 70 2 35 5 14 7 10 So now we have But we’re not finished yet….
Since we multiplied in the beginning, we need to divide in the end. Divide each constant by a. Simplify, if possible. Clear the fraction in each binomial factor
Recall Multiply a times c. List factors. Write 2 binomials with the factors that add to b Divide each constant by a. Simplify, if possible. Clear the fractions in each factor Try some others!
Now you try. Click here when you are ready to check your answers!
(2x-1)(x+5) (2x+5)(x+1) (2x-5)(2x+1) (4x+5)(x-1) Go on to trinomials that have a GCF
Sometimes there is a GCF. If so, factor it out first. 1 30 2 15 3 10 5 6
Now you try. 1. 2. Click here when you are ready to check your answers!
Recall First factor out the GCF. Then factor the remaining trinomial. 9 times 2 = 18 1 18 2 9 3 6 Try some others!
1. 6(x-1)(x+6) (6x+6)(x-6) 2. 2(2x+1)(x+5) 2(2x+5)(x+1)
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Good Job!You have completed factoring “When c is positive and b is positive”!
Good Job!You have completedfactoring “When c is positive and b is negative”!
Good Job! You have completed factoring “When a does not equal 1”!