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Leto [7]
3 years ago
10

Use the substitution method to solve the system of equations. y=7x +8 y=x +20​

Mathematics
1 answer:
DanielleElmas [232]3 years ago
3 0

Answer:

<h2>x = 2, y = 22 → (2, 22)</h2>

Step-by-step explanation:

\left\{\begin{array}{ccc}y=7x+8&(1)\\y=x+20&(2)\end{array}\right\qquad\text{substitute (1) to (2):}\\\\7x+8=x+20\qquad\text{subtract 8 from both sides}\\7x=x+12\qquad\text{subtract x from both sides}\\6x=12\qquad\text{divide both sides by 6}\\x=2\\\\\text{put the value of x to (2):}\\\\y=2+22\\y=22

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A student solved a system of equations by elimination. Describe and correct the error made in the part of the solution shown.
ivanzaharov [21]

Answer:

x = -2; y = 3

Step-by-step explanation:

5x + 4y = 2 (1)

3x + 3y = 3 (2)

Multiply (1) by 3 and (2) by 4

15x + 12y = 6 (3)

12x + 12y = 12 (4)

Subtract (4) from (3)

15x - 12x = 6 - 12

3x = -6

x = -6/3

x = -2

Substitute x = -2 into (1)

5x + 4y = 2

5(-2) + 4y = 2

-10 + 4y = 2

4y = 2 +10

4y = 12

y = 12/4

y = 3

The first error is when he multiplied equation (2) by 4

He didn't multiply the right hand side of the equation by 4

3x + 3y = 3 ×4

12x + 12y = 12

But he wrote

12x + 12y = 3

The the next error is subtracting the left hand side of the equation and adding the right hand side

15x + 12y = 6

12x + 12y = 3

He wrote

3x = 9

Instead of 3x = 3

7 0
3 years ago
Simplify the expression. 7(3x + 5y) + 4y
Butoxors [25]
=21x + 35y + 4y
= 21x + 39y
5 0
3 years ago
Leroy's total job benefits were $50,150 last year. His total job expenses for traveling and for professional development for the
kykrilka [37]

Answer:

D. $53,650

Hope this helps, sorry if it's wrong :)

7 0
3 years ago
Dennis and Eduardo are studying transformations using triangles. A ABC and A DEF are both plotted on a coordinate plane
Talja [164]

Answer:

i think they are

Step-by-step explanation:

8 0
3 years ago
Every day Kim practice volleyball and clarinet each day she practices volleyball for 2.5 hours if after a days she practices bot
AlexFokin [52]

Correct question:

Every day Kim practice volleyball and clarinet each day she practices volleyball for 2.5 hours if after 8 days she practices both volleyball and the clarinet for a total of 36 hours how many hours per day did Kim practice clarinet.

Answer: 2 hours

Step-by-step explanation:

Everyday Kim practices volleyball and clarinet = v/ball + clarinet

Everyday volleyball practice = 2.5hours

That is clarinet(hours) + 2.5 hours of volleyball

After 8 day, total practice hours of both volleyball and clarinet equals 36 hours

The above information can be represented mathematically as thus:

Let h = hours per day of clarinet

8(h + 2.5) = 36

8h + 20 = 36

8h = 36 - 20

8h = 16

h = 16/8

h = 2

6 0
4 years ago
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