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3 years ago

Please help I'm very confused

Mathematics

1 answer:

user100 [1]3 years ago

4 0

Answer:

C and D

Step-by-step explanation:

You have to use the distributive property.

C. 9 times y is 9y and 9 times 7 is 63

D. 3 times 3y is 9y and 3 times 21 is 63

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1 and 3/4 + 2 and 3/8

MariettaO [177]

Hello There!

1 $\frac{3}{4}$ + 2 $\frac{3}{8}$ = 4 $\frac{1}{8}$

First, when we are trying to find the sum of a mixed number, I always add the natural numbers first meaning that the numbers before the fraction so I would add 1 and 2 together so we get a sum of 3 and now we are left with just a plain fraction.

Next, I find the least common denominator which is the smallest number that can be a common denominator for a set of fractions. Our lowest common denominator is 8 because $\frac{3}{4}$ = $\frac{6}{8}$ .

Then, we add our fractions with the denominator of 8 together and get a sum of 9/8 which we can turn into a mixed number because the numerator is bigger than our denominator.

Our mixed number turns into 1 and 1/8 and we add 4 to it because that was the sum of our natural numbers and get a sum of 4 and 1/8

ANSWER 4 1/8

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3 years ago

What is the variable in this expression? 5x^2 + x+7

Zinaida [17]

Answer:

its x

Step-by-step explanation:

hope it helps unlike that other person

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3 years ago

How do you identify the angle of rotation including the direction

yarga [219]

In rotation, the angle through which the plane figure is rotated is called the point of a figure through a specified angle and direction about a fixed point. Identify the corresponding vertices of the rotation.

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3 years ago

Help! Please! Im Failing :'

Naddika [18.5K]

Answer:

3.) D

4.) B

Step-by-step explanation:

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3 years ago

I can't figure out how to do (i + j) x (i x j)for vector calc

Vinil7 [7]

In three dimensions, the cross product of two vectors is defined as shown below

$\begin{gathered} \vec{A}=a_1\hat{i}+a_2\hat{j}+a_3\hat{k} \\ \vec{B}=b_1\hat{i}+b_2\hat{j}+b_3\hat{k} \\ \Rightarrow\vec{A}\times\vec{B}=\det (\begin{bmatrix}{\hat{i}} & {\hat{j}} & {\hat{k}} \\ {a_1} & {a_2} & {a_3} \\ {b_1} & {b_2} & {b_3}\end{bmatrix}) \end{gathered}$

Then, solving the determinant

$\Rightarrow\vec{A}\times\vec{B}=(a_2b_3-b_2a_3)\hat{i}+(b_1a_3+a_1b_3)\hat{j}+(a_1b_2-b_1a_2)\hat{k}$

In our case,

$\begin{gathered} (\hat{i}+\hat{j})=1\hat{i}+1\hat{j}+0\hat{k} \\ \text{and} \\ (\hat{i}\times\hat{j})=(1,0,0)\times(0,1,0)=(0)\hat{i}+(0)\hat{j}+(1-0)\hat{k}=\hat{k} \\ \Rightarrow(\hat{i}\times\hat{j})=\hat{k} \end{gathered}$

Where we used the formula for AxB to calculate ixj.

Finally,

$\begin{gathered} (\hat{i}+\hat{j})\times(\hat{i}\times\hat{j})=(1,1,0)\times(0,0,1) \\ =(1\cdot1-0\cdot0)\hat{i}+(0\cdot0-1\cdot1)\hat{j}+(1\cdot0-0\cdot1)\hat{k} \\ \Rightarrow(\hat{i}+\hat{j})\times(\hat{i}\times\hat{j})=1\hat{i}-1\hat{j} \\ \Rightarrow(\hat{i}+\hat{j})\times(\hat{i}\times\hat{j})=\hat{i}-\hat{j} \end{gathered}$

Thus, (i+j)x(ixj)=i-j

8 0

1 year ago