All categories

2 years ago

Factorise and solve : x^3-x^2-4x+4

Mathematics

1 answer:

Alika [10]2 years ago

6 0

(x - 1)(x - 2)(x + 2)

note that the sum of the coefficients 1 - 1 - 4 + 4 = 0

thus x = 1 is a root and (x - 1 ) is a factor

dividing x³ - x² - 4x + 4 by (x - 1)

x³ - x² - 4x + 4 = (x - 1)(x² - 4 ) (note (x² - 4 ) is a difference of squares )

x³ - x² - 4x + 4 = (x - 1)(x - 2)(x + 2)

(x - 1)(x - 2)(x + 2 ) =0

x - 1 = 0 ⇒ x = 1

x - 2 = 0 ⇒ x = 2

x + 2 = 0 ⇒ x = - 2

solutions are x = 1 or x = ± 2

You might be interested in

Avery can run at 10 uph. The bank of a river is represented by the line 4x + 3y = 12, and Avery is at (7, 5). How much time does

Reil [10]

The minimum distance will be along a perpendicular line to the river that passes through the point (7,5)

4x+3y=12

3y=-4x+12

y=-4x/3+12/3

So a line perpendicular to the bank will be:

y=3x/4+b, and we need it to pass through (7,5) so

5=3(7)/4+b

5=21/4+b

20/4-21/4=b

-1/4=b so the perpendicular line is:

y=3x/4-1/4

So now we want to know the point where this perpendicular line meets with the river bank. When it does y=y so we can say:

(3x-1)/4=(-4x+12)/3 cross multiply

3(3x-1)=4(-4x+12)

9x-3=-16x+48

25x=51

x=51/25

x=2.04

y=(3x-1)/4

y=(3*2.04-1)/4

y=1.28

So now that we know the point on the river that is closest to Avery we can calculate his distance from that point...

d^2=(x2-x1)^2+(y2-y1)^2

d^2=(7-2.04)^2+(5-1.28)^2

d^2=38.44

d=√38.44

d=6.2 units

Since he can run at 10 uph...

t=d/v

t=6.2/10

t=0.62 hours (37 min 12 sec)

So it will take him 0.62 hours or 37 minutes and 12 seconds for him to reach the river.

8 0

2 years ago

Garrett has deposited 519 in a savings account that earns interest at a rate of 4.2% compounded daily. What will the account bal

kipiarov [429]

$1059.83 Use this formula:
$A=P(1+r/n) ^{nt}$

P=principal of 519
r= your rate of 4.2% as a decimal
n=number of compounding periods; yours is daily or 365 day in a year.
t=time involved of the investment in years; yours is 17

7 0

3 years ago

Need to be able to check this assignment for my son and I have no clue how to make sure it's correct anyone?

saw5 [17]

Answer:

it is correct

Step-by-step explanation:

4 0

3 years ago

What is the vertex of g(x) = –3x2 + 18x + 2?

blsea [12.9K]

Answer:

$(3,29)$

Step-by-step explanation:

There is a formula that can be used to find the x-value of the vertex of the parabola. This formula is $x=\frac{-b}{2a}$

We have the function $g(x)=-3x^2+18x+2$

From this function, we can find that

$a=-3\\b=18\\c=2$

We can plug in our know values into the formula to get

$x=\frac{-18}{2(-3)\\} \\x=\frac{-18}{-6} \\\\x=3$

Then we can plug in our x-value to find the y-value of the vertex

$g(3)=-3(3)^2+18(3)+2\\\\g(3)=-3(9)+54+2\\\\g(3)=-27+54+2\\\\g(3)=29$

This means that the vertex would be $(3,29)$

6 0

3 years ago

(x+3)^2 + 16/(x+3)^2 = 92 <br><br> x + 1/(x+3) = ??

Irina-Kira [14]

One
Remark
This is very complicate unless you pick the right method. It's very handy o know about substitutions.

Method
Let z = (k + 2)^2

Now the problem becomes
z + 16/z = 92 Multiply through by z

Solution
z^2 + 16 = 92z
That does not look very promising. If you know the quadratic formula, this mess can be solved. If you do not know what the quadratic formula is, then what I've written is the answer.

Worse yet, you have to know what complex numbers are. Is this something you know about? The z form of this equation is fine. It gives answers that are rational. The problem is that both are negative and so in your next step, you will be forced to take the square root of a negative number.

Maybe the answer is just
(x + 3)^ + 16 = 92(x + 3)^2
If all you have to do is expand this then you get
x^2 + 6x + 9 + 16 = 92(x^2 + 6x + 9) Remove the brackets.
x^2 + 6x + 25 = 92x^2 + 552x + 828 Put the left over to the right.
0 = 92x^2 - x^2 + 552x - 6x + 828 - 25
0 = 91x^1 + 546x + 803

It looks that way from the second question. If I'm wrong about that, put a comment down below.

Two
Put over a common denominator and expand
$\frac{(x + 3)^2 + 1}{(x + 3)^2} = \frac{x^2 + 6x + 9 + 1}{x^2 + 6x + 9} = \frac{x^2 + 6x + 10}{x^2 + 6x + 9}$

3 0

2 years ago