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Really need help on this

Really need help on this-example-1
User Azania
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1 Answer

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13 votes

Answer:

x = 3, x = 1

Explanation:

Okay, let's set the equation = 0:

3x^2 -12x + 9 = 0

Then, we factorise. To do this, we have to find 2 numbers which have a product of 9 and add up to -12. There are a few ways to do this, but a simple try and error is the easier when using numbers which don't have many factors. So here we know that to get a product of 9, there are only 2 options: 9*1 and 3*3. Now we have to figure out which of these add up to -12. But to do this, we have to take into account the 3, from the x^2 coefficient. This allows to know that the numbers will be 9*1. Then we just need to change the signs to make it work. This would give: -9*-1 (with 3*-1).

The fully factorised equation would be (3x-9)(x-1). Following this, you can always expand it quickly, to check that it really works correctly.

Now let's solve. (3x-9)(x-1) = 0

We say that when two numbers multiplied by each other equal to zero, one of them has to be zero. So if (3x - 9) was equal to 0:

3x - 9 = 0

3x = 9

x = 9/3

x = 3/1

x = 3

Now for the other:

x - 1 = 0

x = 1

User Huang Tao
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