All categories

3 years ago

Factor 2) x2 – 3x – 18

Mathematics

1 answer:

Anna71 [15]3 years ago

6 0

Answer:

By inspection you need 2 numbers that multiply together to 18 and sum to 3. These numbers are 6 and 3. Therefore we have to find the value of x but we dont have that so we have this:

x to the power of 2-3x - 18 = ( X - 6) ( x + 3)

You might be interested in

Evaluate f(x)=-2x-5 for x=3

RoseWind [281]

Answer:

Step-by-step explanation:

hello :

f(3)=-2(3)-5 = -6-5 = -11

8 0

4 years ago

If you have a cubic polynomial of the form y = ax^3 + bx^2 + cx + d and lets say it passes through the points (2,28), (-1, -5),

nikklg [1K]

Step-by-step explanation:

Step 1: Solve using the first point

(2, 28)

$28 = a(2)^3 + b(2)^2 + c(2) + d$

$28 = 8a + 4b + 2c + d$

Step 2: Solve using the second point

(-1, -5)

$-5 = a(-1)^3 + b(-1)^2 + c(-1) + d$

$-5 = -a + b - c + d$

Step 3: Solve using the third point

(4, 220)

$220 = a(4)^3 + b(4)^2 + c(4) + d$

$220 = 64a + 16b + 4c + d$

Step 4: Solve using the fourth point

(-2, -20)

$-20 = a(-2)^3 + b(-2)^2 + c(-2) + d$

$-20 = -8a + 4b - 2c + d$

Step 5: Combine the first and fourth equations

$28 - 20 = 8a - 8a + 4b + 4b + 2c - 2c + d + d$

$8 = 8b + 2d$

$8 - 8b = 8b - 8b + 2d$

$(8 -8b)/2 = 2d/2$

$4 - 4b = d$

Step 6: Solve for c in the second equation

$-5 + 5 = -a + b - c + d + 5$

$0 + c = -a + b - c + c + d + 5$

$c = -a + b + d + 5$

Step 7: Substitute d with the stuff we got in step 5

$c = -a + b + (4 - 4b) + 5$

$c = -a + b + 4 - 4b + 5$

$c = -a - 3b + 9$

Step 8: Substitute d and c into the first equation

$28 = 8a + 4b + 2(-a - 3b + 9) + (4 - 4b)$

$28 = 8a + 4b - 2a - 6b + 18 + 4 - 4b$

$28 - 22 = 6a - 6b + 22 - 22$

$6 / 6 = (6a - 6b) / 6$

$1 + b = a - b + b$

$1 + b = a$

Step 9: Substitute a, b, and c into the third equation

$220 = 64(1 + b) + 16b + 4(-(1 + b) - 3b + 9) + (4 - 4b)$

$220 = 64 + 64b + 16b + 4(-1 - b - 3b + 9) + 4 - 4b$

$220 - 100 = 60b + 100 - 100$

$120 / 60 = 60b / 60$

$2 = b$

Step 10: Find a using b = 2

$a = b + 1$

$a = (2) + 1$

$a = 3$

Step 11: Find c using a = 3 and b = 2

$c = -a - 3b + 9$

$c = -(3) - 3(2) + 9$

$c = -3 - 6 + 9$

$c = 0$

Step 12: Find d using b = 2

$d = 4 - 4b$

$d = 4 - 4(2)$

$d = 4 - 8$

$d = -4$

Answer: $a = 3, b = 2, c = 0,d = -4$

6 0

3 years ago

Read 2 more answers

a painter bought 8 gallons of paint just enough to cover 2 rooms. One room is twice the size of the other and requires only 2 co

e-lub [12.9K]

So, he's got 8 gallons of paint, to paint the two rooms, of the two rooms, one is twice as big as the other

now, "x" is how many gallons to paint the larger room with only one coat, however, the larger room uses 2 coats, so, the larger room uses 2x of paint
now, the client declined to paint the smaller one

so hmmm as I read... well, we dunno how many coats will go to the smaller room for one, we know the larger will use 2 coats, or 2x.. if we assume the smaller room was going to use say 1 coat or 1/2x

then one can say the painter bought enough for both rooms, 1coat for the small one and 2coats for the larger one

so, the paint the larger room, you'll 2x of paint, for 2coatsand to paint the smaller room, you'll need 1/2 x, because x gallons is how much is needed for the larger room, but the larger room is twice as big, thus the smaller room uses 1/2 of that in gallons

thus, with those assumptions, that the small room will use only 1 coat
$\bf \cfrac{1}{2}x+2x=8\implies \cfrac{5x}{2}=8\implies x=\cfrac{16}{5}$
that's who many gallons are needed for 1 coat in the larger roomrecall "x" is 1coat for the larger room

now, the client decides to skip the smaller roomso, the painter will only need 2x gallons then

$\bf 2x\implies 2\cdot \cfrac{16}{5}\implies \cfrac{32}{5}\implies 6.4\ gallons$

he bought 8 gallons, 8 - 6.4, he's got left 1.6 gallons

3 0

3 years ago

Read 2 more answers

Use the reference angles to find the exact value of the expression cot -11 pi/6. Do not use a calculator

laiz [17]

Answer:

$\sqrt{3}$