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irina1246 [14]
4 years ago
15

How to do these problems

Mathematics
1 answer:
topjm [15]4 years ago
5 0
\bf \begin{array}{llcll}
3x-y=7&&3x-y=7\\
x+y=-11&\boxed{\times -3}\implies &-3x-3y=33\\
&&-------\\
&&0-4y=40
\end{array}\\\\
y=\cfrac{40}{-4}\implies y=-10\\\\
-----------------------------\\\\

\begin{array}{cllll}
x-7y=-9\\
-x+8y=10\\
--------\\
0+y=1
\end{array}\\\\
-----------------------------\\\\

\begin{array}{llcll}
7x+y=14&\boxed{\times -3}\implies &-21x-3y=-42\\
8x+3y=16&&8x+3y=16\\
&&--------\\
&&-13x+0=-26
\end{array}
\\\\
x=\cfrac{-26}{-13}\implies x=2

notice, the 2nd one, had a x and -x, so, we don't have to multiply anything there, just cancel those two out
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Fully Factor 3x^2 – 16x + 20
ryzh [129]

Answer:

C. (3x2 - 10) (x - 2)

Step-by-step explanation:

3x^2 - 16x +20

Step 1: Sum = - 16x

Product = 60x^2

Step 2: Find 2 numbers that their sum is -16 and their product is 60. If you do that correctly, then you will get two numbers: 10 and -6

Step 3: Replace -16x with the two numbers found in step 2, then you will have; 3x^2 - 6x - 10x + 20

Step 4: Factorise the equation in step 3, like so;

(3x^2 - 6x)(- 10x + 20)

3x(x - 2) -10(x - 2)

(3x - 10)(x - 2)

To check if the answer is correct, expand the bracket: (3x - 10)(x - 2)

If the bracket is opened properly, you will get 3x^2 - 16x + 20

4 0
3 years ago
50 POINTS + BRAINLIEST
Vedmedyk [2.9K]
X + 2y = 6
2y = -x + 6
  y = -1/2 x + 3 so slope = -1/2

parallel lines  has same slope = -1/2
perpendicular lines slope is opposite and reciprocal so slope = 2  
if slope not equal either -1/2 or 2 then neither.

y = -1/2 x - 5 ....m= - 1/2....  parallel

-2x + y = -4
          y = 2x - 4...m = 2 ....perpendicular

-x + 2y = 2
2y = x + 2
y = 1/2 x + 1 ...m = 1/2 ...neither

x + 2y = -2
2y = -x - 2
 y = -1/2 x - 1 ...m = -1/2 .....parallel

hope it helps
3 0
3 years ago
Read 2 more answers
If maria paid her supplier $8.50/doz for roses and sold them for $19.95,what was the percent markup?
Shkiper50 [21]

Answer: 42.6% or you can round it to 43%


Step-by-step explanation:


6 0
3 years ago
1) What is 20% of 20?<br> 2) what is 15 is what percent of 30?<br> 3) 50 is 50% of what?
N76 [4]

Hi there!

The word "of" is the same thing as a multiplication sign.

1)

20% = 0.2

0.2 × 20 = 4


2)

? × 30 = 15

divide each side of the equation by 30

? = 0.5

0.5 = 50%


3)

50% = 0.5

0.5 × ? = 50

divide each side of the equation by 0.5

? = 100


There you go! I really hope this helped, if there's anything just let me know! :)

7 0
3 years ago
Read 2 more answers
I GIVEEEEE BRAINLILST
Pavel [41]

Answer:

73.5

Step-by-step explanation:

HOYAAAAAAAAJIIJUJJ

8 0
3 years ago
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