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2 years ago

2x(x - 3) + 7(x - 3) Can I have an explanation on how it works factors

Mathematics

1 answer:

Nimfa-mama [501]2 years ago

8 0

Answer:

Step-by-step explanation:

2x(x - 3) + 7(x - 3)

2x^2 - 6x + 7x - 21

reduce

2x^2 + x - 21

if this is equal to 0 then:

2x^2 + x - 21 = 0

factored:

(2x + 7)(x - 3) = 0

How that was done:

Divide the (2x^2) into (2x) and (x).

Divide the (-21) into (+7) and (-3). You choose these numbers so that their sum, when multiplied by (2x) and (-3), adds up to (+x).

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Separate non-x terms from x terms

wel

Answer:X^2-7X=57/4

Step-by-step explanation:

Y=X^2-7X+57/4

X^2-7X=57/4

6 0

2 years ago

The vector (a) is a multiple of the vector (2i +3j) and (b) is a multiple of (2i+5j) The sum (a+b) is a multiple of the vector (

kow [346]

Answer:

$\|a\| = 5\sqrt{13}$ .

$\|b\| = 3\sqrt{29}$ .

Step-by-step explanation:

Let $m$ , $n$ , and $k$ be scalars such that:

$\displaystyle a = m\, (2\, \vec{i} + 3\, \vec{j}) = m\, \begin{bmatrix}2 \\ 3\end{bmatrix}$ .

$\displaystyle b = n\, (2\, \vec{i} + 5\, \vec{j}) = n\, \begin{bmatrix}2 \\ 5\end{bmatrix}$ .

$\displaystyle (a + b) = k\, (8\, \vec{i} + 15\, \vec{j}) = k\, \begin{bmatrix}8 \\ 15\end{bmatrix}$ .

The question states that $\| a + b \| = 34$ . In other words:

$k\, \sqrt{8^{2} + 15^{2}} = 34$ .

$k^{2} \, (8^{2} + 15^{2}) = 34^{2}$ .

$289\, k^{2} = 34^{2}$ .

Make use of the fact that $289 = 17^{2}$ whereas $34 = 2 \times 17$ .

$\begin{aligned}17^{2}\, k^{2} &= 34^{2}\\ &= (2 \times 17)^{2} \\ &= 2^{2} \times 17^{2} \end{aligned}$ .

$k^{2} = 2^{2}$ .

The question also states that the scalar multiple here is positive. Hence, $k = 2$ .

Therefore:

$\begin{aligned} (a + b) &= k\, (8\, \vec{i} + 15\, \vec{j}) \\ &= 2\, (8\, \vec{i} + 15\, \vec{j}) \\ &= 16\, \vec{i} + 30\, \vec{j}\\ &= \begin{bmatrix}16 \\ 30 \end{bmatrix}\end{aligned}$ .

$(a + b)$ could also be expressed in terms of $m$ and $n$ :

$\begin{aligned} a + b &= m\, (2\, \vec{i} + 3\, \vec{j}) + n\, (2\, \vec{i} + 5\, \vec{j}) \\ &= (2\, m + 2\, n) \, \vec{i} + (3\, m + 5\, n) \, \vec{j} \end{aligned}$ .

$\begin{aligned} a + b &= m\, \begin{bmatrix}2\\ 3 \end{bmatrix} + n\, \begin{bmatrix} 2\\ 5 \end{bmatrix} \\ &= \begin{bmatrix}2\, m + 2\, n \\ 3\, m + 5\, n\end{bmatrix}\end{aligned}$ .

Equate the two expressions and solve for $m$ and $n$ :

$\begin{cases}2\, m + 2\, n = 16 \\ 3\, m + 5\, n = 30\end{cases}$ .

$\begin{cases}m = 5 \\ n = 3\end{cases}$ .

Hence:

$\begin{aligned} \| a \| &= \| m\, (2\, \vec{i} + 3\, \vec{j})\| \\ &= m\, \| (2\, \vec{i} + 3\, \vec{j}) \| \\ &= 5\, \sqrt{2^{2} + 3^{2}} = 5 \sqrt{13}\end{aligned}$ .

$\begin{aligned} \| b \| &= \| n\, (2\, \vec{i} + 5\, \vec{j})\| \\ &= n\, \| (2\, \vec{i} + 5\, \vec{j}) \| \\ &= 3\, \sqrt{2^{2} + 5^{2}} = 3 \sqrt{29}\end{aligned}$ .

6 0

2 years ago

Sofia and Diego drive to work. Sofia drives 72 miles in 1.5 hours. Diego drives 126 km in 2 hour 30 min. Work out the difference

sdas [7]

Answer:

26.4 km/hr

Step-by-step explanation:

Sofia and Diego drive to work.

For Sofia

We convert miles to km

Sofia drives 72 miles in 1.5 hours.

1 mile = 1.6 km

72 miles = x

x = 72 × 1.6 km

x = 115.2 km

We find the speed in km/hr

Speed = Distance /Time

= 115.2km/1.5 hours

= 76.8 km/hr

For Diego

Diego drives 126 km in 2 hour 30 min.

Speed = Distance/Time

Time = 2 hour 30 min = 2.5 hours

Speed = 126km/2.5 hours

= 50.4 km/hr

The difference between their average speeds in km/h is calculated as:

76.8 km/hr - 50.4 km/hr

= 26.4 km/hr

5 0

2 years ago

What is 1/2 of 14? this is an algebraic expression!!

Vikentia [17]

1/2 of 14 is 7. multiply 14/1 to 1/2.

3 0

2 years ago

Help. please <br><br><br> &-&-&-&/&/&/$72

DIA [1.3K]

Answer:

Step-by-step explanation:

Enter your x and y values into your equation from your table

7 0

2 years ago

Read 2 more answers