How to solve x+7y=0 2x-8y=20

1 answer:

8 0

Solve the following system:
{x + 7 y = 0 | (equation 1)
{2 x - 8 y = 20 | (equation 2)

Swap equation 1 with equation 2:
{2 x - 8 y = 20 | (equation 1)
{x + 7 y = 0 | (equation 2)

Subtract 1/2 × (equation 1) from equation 2:
{2 x - 8 y = 20 | (equation 1)
{0 x+11 y = -10 | (equation 2)

Divide equation 1 by 2:
{x - 4 y = 10 | (equation 1)
{0 x+11 y = -10 | (equation 2)

Divide equation 2 by 11:
{x - 4 y = 10 | (equation 1)
{0 x+y = (-10)/11 | (equation 2)

Add 4 × (equation 2) to equation 1:
{x+0 y = 70/11 | (equation 1)
{0 x+y = -10/11 | (equation 2)
Collect results:
Answer: {x = 70/11
{y = -10/11

You might be interested in

WHAT IS THE STANDARD FORM OF 5.93e-5?

Valentin [98]

The answer to question above is 0.0000593

3 0

3 years ago

I need help with these two questions

BlackZzzverrR [31]

Problem 4

Answer: 47

------------------------

Work Shown:

f(x) = x^2 - 7x + 3
f(x) = (x)^2 - 7(x) + 3
f(-4) = (-4)^2 - 7(-4) + 3 ... replace each x with -4
f(-4) = 16 - 7(-4) + 3
f(-4) = 16 + 28 + 3
f(-4) = 44 + 3
f(-4) = 47

============================================================

Problem 5

Answer: See the attached image for the table

------------------------

Work Shown:

Plug in n = 27 and we get...
C = 26 + 10*n
C = 26 + 10*27
C = 26 + 270
C = 296
The input n = 27 leads to the output C = 296. This means that 27 people will have the cost be $296

Do the same for n = 39
C = 26 + 10*n
C = 26 + 10*39
C = 26 + 390
C = 416
The input n = 39 leads to the output C = 416. This means that 39 people will have the cost be $416

and also n = 43 as well
C = 26 + 10*n
C = 26 + 10*43
C = 26 + 430
C = 456
The input n = 43 leads to the output C = 456. This means that 43 people will have the cost be $456