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charle [14.2K]
3 years ago
7

Factor x2 - 18x + 81. Show your work

Mathematics
2 answers:
tensa zangetsu [6.8K]3 years ago
4 0
To factorise it start with putting the xs in brackets.
(x )(x )
Then you must find 2 numbers which multiply to +81 and sum to -18.
81 is the product of 9×9 or -9×-9.
9+9=+18
-9+-9=-18
So they two numbers must be -9.
So factorised it is (x-9)(x-9) or (x-9)^2
Korvikt [17]3 years ago
4 0
(x - 9)^2

Whenever dealing with a problem like this the first thing you should consider is a square in the last term. Factoring trinomials is always a guess and check procedure, but there are multiple tips to enhance and quicken your guessing. When the last term is a positive square, find the square root of it and double it. Chances are, that result will be the middle term. It is only a matter of addition of subtraction now. If the middle term is negative then it is a subtraction, and if the middle term is positive then vice versa. 

81 is a positive square and the square root is 9. By doubling it you get 18. The middle term is negative, so the binomial squared is (x - 9). Hope this helps!
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5 0
1 year ago
What is the value of n in the equation –1/2(2n + 4) + 6 = –9 + 4(2n + 1)?
ioda

Answer:

<h2>n = 1</h2>

Step-by-step explanation:

-\dfrac{1}{2}(2n-4)+6=-9+4(2n+1)\qquad\text{use the distributive property}\\\\\left(-\dfrac{1}{2}\right)(2n)+\left(-\dfrac{1}{2}\right)(-4)+6=-9+(4)(2n)+(4)(1)\\\\-n-2+6=-9+8n+4\qquad\text{combine like terms}\\\\-n+(-2+6)=8n+(-9+4)\\\\-n+4=8n-5\qquad\text{subtract 4 from both sides}\\\\-n=8n-9\qquad\text{subtract}\ 8n\ \text{from both sides}\\\\-9n=-9\qquad\text{divide both sides by (-9)}\\\\n=1

7 0
3 years ago
9. Determine if x + 1 is a factor of x ^ 4 - 4x ^ 2 - 4x - 1 Justify your answer.
Elden [556K]

Answer:

No

Step-by-step explanation:

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5 0
2 years ago
Descried how to derive the quadratic formula from a quadratic equation in standard form
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Answer:

The standard form of a quadratic equation is:

ax^2+bx+c=0, a\neq 0

Quadratic Formula Derivation:

ax^2+bx+c=0\\

$x^2+\frac{b}{a}x+\frac{c}{a} =0 $

$x^2+\frac{b}{a}x = -\frac{c}{a}$

Completing the Square:

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Square Root property:

$x+\frac{b}{2a}  = \pm \sqrt{ \frac{b^2-4ac}{4a^2}}   $

$x  = -\frac{b}{2a} \pm  { \frac{\sqrt {b^2-4ac}}{2a}}   $

$x  =  \frac{-b\pm\sqrt{b^2-4ac}} {2a}  }   $

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Naily [24]

Answer:

$4.33

Step-by-step explanation:

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1 hour -> $13/3 = $4.33

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