Solve by factoring:x^2 – 5x = 6?

2008-12-26 1:13 am

回答 (12)

2008-12-26 1:12 pm
✔ 最佳答案
Hi!!

Let's do it:

x² - 5x = 6;
x² - 5x + 6 = 0;

Now we must factorise that expression, x² - 5x - 6. To factor it we should try to divide it using Ruffini's method with the divisors of the independent term, 6.

6 = 2 ∙ 3.

The divisors are 1, -1, 2, -2, 3, -3, 6 and -6.

Let's divide it by x - 1.

(x² - 5x - 6)/(x - 1)

It isn't a exact division. 1 isn't a root.

Let's divide it by x + 1.

(x² - 5x - 6)/(x + 1) = (x - 6)

It IS a exact division. -1 and 6 are roots.

Therefore the factored form is:

x² - 5x - 6 = (x - 6)(x + 1)

We can now reinsert it into the equation:

(x - 6)(x + 1) = 0;
x - 6 = 0, x = 6
x + 1 = 0; x = -1

∴ x = 6 and x = -1

Well, bye hope it helped, Happy Xmas :D!!
參考: Self-Knowledge
2008-12-26 5:25 am
x² - 5x = 6
x² - 5/2x = 6 + (- 5/2)²
x² - 5/2x = 24/4 + 25/4
(x - 5/2)² = 49/4
x - 5/2 = 7/2

= x - 5/2 - 7/2, = x - 12/2, = x - 6
= x - 5/2 + 7/2, = x + 2/2, = x + 1

x - 6 = 0, x = 6
x + 1 = 0, x = - 1

Answer: x = 6, - 1; (x - 6)(x + 1) are the factors.

Proof (x = 6):
6² - 5(6) = 6
36 - 30 = 6
6 = 6

Proof (x = - 1):
- 1² - 5(- 1) = 6
1 + 5 = 6
6 = 6

Proof (F.O.I.L.):
(x - 6)(x + 1) = 0
x² + x - 6x - 6 = 0
x² - 5x - 6 = 0
x² - 5x = 6
2017-01-06 4:15 pm
ok, it extremely is technically the place a logarithm comes into play. in case you haven't any longer finished that earlier, it extremely is wonderful, i'm going to attempt to make it simple. because of the fact the x is an component to our exponent, you're able to desire to hold it down. You do this by using looking go browsing the two aspects. log(3)(5x-6) = log(80 one) We in simple terms positioned the three in parentheses because of the fact it extremely is how we carry down our exponent. Now divide log(80 one) by using log(3) 5x-6 = log(80 one)/log(3) you do no longer could desire to comprehend the thank you to do it extremely in case you have a calculator. i'm no longer likely to instruct you the artwork. besides the undeniable fact that, your answer for log(80 one)/log(3) = 4 (this suggests in case you probably did 3^4 you may get 80 one) we now have 5x-6 = 4 flow the 6 over to the impressive 5x = 10 Divide out 5. x = 2 Now in case you knew that 80 one grew to become into 3^4 already, you probable could have finished this interior the shorter way. i'm in simple terms coaching the log factor because of the fact each and every now and then you will no longer comprehend the precise exponent. I was hoping that helped.
2008-12-26 3:03 pm
Question Number 1 :
For this equation x^2 - 5*x = 6 , answer the following questions :
A. Use factorization to find the root of the equation !

Answer Number 1 :
First, we have to turn equation : x^2 - 5*x = 6 , into a*x^2+b*x+c=0 form.
x^2 - 5*x = 6 , move everything in the right hand side, to the left hand side of the equation
<=> x^2 - 5*x - ( 6 ) = 0 , which is the same with
<=> x^2 - 5*x + ( - 6 ) =0 , now open the bracket and we get
<=> x^2 - 5*x - 6 = 0

The equation x^2 - 5*x - 6 = 0 is already in a*x^2+b*x+c=0 form.
In that form, we can easily derive that the value of a = 1, b = -5, c = -6.

1A. Solve by Factorization

x^2 -5*x -6 = 0
Separate : ( x^2 +x ) + ( -6*x -6 ) = 0
Commutative Law : ( x^2 -6*x ) + ( x -6 ) = 0
Distributive Law : x*( x -6 ) + +*( x -6 ) = 0
Factor : ( x +1 )*( x -6 ) = 0

So the Polynomial have 2 roots :
x1 = -1
x2 = 6
2008-12-26 9:57 am
x² - 5x - 6 = 0
(x - 6)(x + 1) = 0
x = 6 , x = - 1
2008-12-26 1:51 am
x^2-5x=6
x^2-5x-6=0
(x-6)(x+1)=0
x=6 or -1
2008-12-26 1:47 am
x^2 - 5x = 6
x^2 - 5x - 6 = 0
x^2 + x - 6x - 6 = 0
(x^2 + x) - (6x + 6) = 0
x(x + 1) - 6(x + 1) = 0
(x + 1)(x - 6) = 0

x + 1 = 0
x = -1

x - 6 = 0
x = 6

∴ x = -1 , 6
2008-12-26 1:17 am
Subtract 6 so you get x^2 - 5x -6 = 0, then factor that equation.

(x+1)(x-6)
2008-12-26 1:17 am
x^2 - 5x = 6

Your first step is to bring everything to the left hand side.

x^2 - 5x - 6 = 0

Next, factor this as normal. As a reminder, you want to look for two factors of the third term (-6) that add up to the middle term (-5).

(x + ?)(x + ?) = 0

These two numbers are: -6 and +1. Those go in the question marks.

(x - 6)(x + 1) = 0

Equate each term to 0 to solve for possible values of x.

x - 6 = 0
x = 6

x + 1 = 0
x = -1

Therefore,
x = {6, -1}
2008-12-26 1:17 am
x^2 – 5x - 6 = 0
(x+1)(x-6)=0
x=-1, x=6


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