X-y+z=-4

3x+2y-z=5

-2x+3y-z=15

How do I solve this?

Answers

Answer 1

Answer: $1)\ \ \ x-y+z=-4\ \ \ \Rightarrow\ \ \ z=-4-x+y\n\n2)\ \ \ 3x+2y-z=5 \n.\ \ \ \ \Rightarrow\ \ 3x+2y-(-4-x+y)=5 \n.\ \ \ \ \Rightarrow\ \ 3x+2y+4+x-y=5 \n.\ \ \ \ \Rightarrow\ \ 4x+y=1\n\n3)\ \ \ -2x+3y-z=15\n.\ \ \ \ \Rightarrow\ \ -2x+3y-(-4-x+y)=15\n.\ \ \ \ \Rightarrow\ \ -2x+3y+4+x-y=15\n.\ \ \ \ \Rightarrow\ \ -x+2y=11\n--------------------\n$

$z=-4-x+y\n.\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ and\n \left \{ {{4x+y=1\ \ \ \ } \atop {-x+2y=11\ /\cdot4}} \right. \n\n\left \{ {{4x+y=1\ \ \ \ } \atop {-4x+8y=44}} \right. \n-------\ny+8y=1+44\n9y=45\ /:9\ny=5\n\n-x+2y=11\ \ \ \Rightarrow\ \ \ x=2y-11\ \ \ \Rightarrow\ \ \ x=2\cdot5-11=-1\n\nz=-4-x+y=-4-(-1)+5=-4+1+5=2\n\nAns.\ x=-1\ \ \ and\ \ \ y=5\ \ \ and\ \ \ z=2$

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Find the range of f(x) = 5 - |x - 4|.

What does ( 7.8 x 10 to the 3rd) x (1.0 x 10 to the 4th) equal?

Answers

Answer:

7.8 * 10^7

Step-by-step explanation:

Group coefficients together and exponents together to multiply numbers in scientific notation.

(7.8 * 1) (10^3 * 10^4)

Multiply 7.8 times 1.

7.8 * (10^3 * 10^4)

Use the power rule a^m * a^n = a^(m+n) to combine exponents. So, add 3 and 4

7.8 * 10^7

2x + y = -2x + y = 5

The x-coordinate of the solution to the system shown is _____.

Answers

The x-coordinate of the solution to the system shown is -7.

Proof:
From the 2nd equation, equate in terms of y:
y = 5 - x
Then substitute it to the first equation:
2x + 5 - x = -2
2x - x = -2 -5
x = -7

HELP ASAP!!!The markup on candy at the discount store is 45%. A bag of candy has a wholesale cost of $1.15. What will be the retail price for the candy?

A. $1.45
B. $1.60
C. $1.67
D. $1.78

Answers

Answer:

Option C. $1.67

Step-by-step explanation:

The price of a bag of candy at wholesale = $1.15

The markup on candy at the discount store = 45%

The retail price for the candy = 1.15 +(45% × 1.15)

= 1.15 + ( $(45)/(100)$ ×1.15)

= 1.15 + (0.45 × 1.15)

= 1.15 + 0.5175

= 1.6675 ≈ $1.67

The retail price for the candy would be $1.67.

The answer is C.$1.67

If x=3 and y=-2 and z=4, what is the value of 3x + 2y - z?

Answers

$3x+2y-z=3\cdot3+2\cdot(-2)-4=9-4-4=1$

3x3=9 -2x2=-4 4-0=4

9+-4-4

ANS. = 1

How many solutions does the system 2y=10x-14 and 5x-y=7 have

Answers

Answer: 1 solution at (2.8, 7)

Answer:

All real numbers

Step-by-step explanation:

Take 2y=10x-14 and divide both sides by 2. Once you do that, you get y=5x-7. Use substitution and plug that into 5x-y=7. You get 5x-(5x-7)=7 which eventually simplifies to 7=7 which shows that you can plug in an infinite number of solutions so the answer is all real numbers.

All equilateral triangles are also isoseles triangles? True or false