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N76 [4]
3 years ago
14

If 3x+2y=12 and -4x+6y=24 what is the value of -x+2y

Mathematics
1 answer:
oksano4ka [1.4K]3 years ago
6 0
(1) 3x+2y=12
(2) -4x+6y=24

Solving the system of equations using the method of substitution:
Isolating y in the first equation:
(1) 3x+2y=12→3x+2y-3x=12-3x→2y=12-3x→2y/2=(12-3x)/2→y=(12-3x)/2

Replacing "y" by (12-3x)/2 in the second equation:
(2) -4x+6y=24
y=(12-3x)/2→-4x+6[(12-3x)/2]=24

Solving for x:
-4x+3(12-3x)=24
-4x+36-9x=24
-13x+36=24
-13x+36-36=24-36
-13x=-12
-13x/(-13)=-12/(-13)
x=12/13

Replacing "x" by 12/13 in y=(12-3x)/2
x=12/13→y=[12-3(12/13)]/2
y=(12-36/13)/2
y={[(13)(12)-36]/13}/2
y=[(156-36)/13]/2
y=(120/13)/2
y=(120/13)(1/2)
y=60/13

x=12/13; y=60/13
-x+2y=-12/13+2(60/13)
-x+2y=-12/13+120/13
-x+2y=(-12+120)/13
-x+2y=108/13

Answer: The value of -x+2y is 108/13 
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The cost for an order of 100 kilograms of steel bars is $230. The cost for an order of 150 kilograms of steel bars is $320. Writ
luda_lava [24]

Answer:

y = 9x/5 + 50

Step-by-step explanation:

We are represent the information as coordinate (x,y)

If the cost for an order of 100 kilograms of steel bars is $230, this is expressed as (100, 230)

Also if the cost for an order of 150 kilograms of steel bars is $320, this is expressed as;

(150, 320)

Find the equation of a line passing through the points. The standard form of the equation is expressed as y = mx+c

m is the slope

c is the intercept

Get the slope;

m = y2-y1/x2-x1

m = 320-230/150-100

m = 90/50

m = 9/5

Get the y-intercept by substituting m = 9/5 and any point say (100, 230) into the expression y = mx+c

230 = 9/5(100)+c

230 = 9(20)+c

230 = 180 + c

c = 230-180

c = 50

Get the required equation

y = mx+c

y = 9/5 x + 50

Hence an equation for the cost of an order of steel bars (y) in terms of the weight of steel bars ordered (x) is y = 9x/5 + 50

4 0
3 years ago
Put the following equation in standard form and determine the quadratic, linear, and constant coefficients. -3x2 - 8 = 5x - 7
marusya05 [52]

Answer:

  • -3x² -5x -1 = 0
  • -3 (quadratic)
  • -5 (linear)
  • -1 (constant)

Step-by-step explanation:

The equation will be in standard form when terms are listed in order of decreasing degree, and the right side of the equation is 0.

<h3>Standard form</h3>

We can subtract the right-side expression from both sides to get standard form.

  -3x² -8 -(5x -7) = 5x -7 -(5x -7)

  -3x² -8 -5x +7 = 0 . . . . . . . simplify a bit

  -3x² -5x -1 = 0 . . . . . . . . . collect terms

The standard form equation can be written ...

  -3x² -5x -1 = 0

<h3>Coefficients</h3>

The quadratic coefficient is the coefficient of the term with degree 2. The quadratic coefficient is -3.

The linear coefficient is the coefficient of the term with degree 1. The linear coefficient is -5.

The constant coefficient is the coefficient of the term with no variables. The constant is -1.

__

<em>Additional comment</em>

We can make the leading coefficient positive by multiplying the equation by -1. This gives ...

  3x² +5x +1 = 0

with quadratic, linear, and constant coefficients 3, 5, 1.

This is a legitimate answer to this question. In the case of linear equations, the "standard form" has the constant on the right side of the equal sign, and the leading coefficient is required to be positive. A negative leading coefficient can sometimes lead to errors (when the sign is overlooked), so having a positive leading coefficient is often preferred.

8 0
2 years ago
6)
Dvinal [7]

Answer:

It has to be x - 9= 27

so it can be x=36

6 0
3 years ago
Read 2 more answers
Please help ASAP!!!!!
LenKa [72]

Answer: first answer choice (1/3)  (p+45)

Step-by-step explanation:

to do this, factor out 1/3 from each element

so divide 1/3 p by 1/3 and 15 by 1/3

(1/3 p) / (1/3 ) = p

15 / (1/3) = 15 * 3 = 45

now put 1/3 outside of the parentheses

(1/3)  (p+45)

8 0
3 years ago
Can somebody help me on this pleaseee
lord [1]

Answer:

B I think or C or D or it could be A

6 0
2 years ago
Read 2 more answers
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