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ladessa [460]
1 year ago
6

Solve the system of equations using substitution y=7 y=2x-5

Mathematics
1 answer:
anzhelika [568]1 year ago
5 0

y= 7 (a)

y= 2x-5 (b)

Replace (a) on (b) ans solve for x:

7 = 2x-5

Add 5 to both sides of the equation:

7+5 = 2x -5 +5

12 = 2x

Divide both sides by 2

12/2 = 2x/2

6 = x

Solution:

x=6, y=7

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How do I solve these systems of equations?
ruslelena [56]
1. -x+9y=-5
x-5y=1
-----------------
x=1+5y
-(1+5y)+9y=-5
-1-5y+9y=-5
-1+4y=-5
4y=-5-(-1)
4y=-5+1=-4
4y=-4
y=-4/4=-1
So x=1+5y=1+5(-1)=1-5=-4
Answer: x=-4, y=-1. (-4, -1).

2) -7x-y=13
8x+y=-14
------------------
y=-14-8x
-7x-(-14-8x)=13
-7x+14+8x=13
14+x=13
x=13-14=-1
y=-14-8(-1)=-14+8=-6.
Answer: x=-1, y=-6. (-1, -6).

3) x+7y=24
x-9y=-24
----------------
x=24-7y
24-7y-9y=-24
24-16y=-24
16y=24-(-24)=24+24=48
y=48/16=3
x=24-7(3)=24-21=3
Answer: x=3, y=3. (3, 3).

4). 3x+y=-21
x+y=-5
-------------------
x=-5-y
3(-5-y)+y=-21
-15-3y+y=-21
-15-2y=-21
2y=-15-(-21)=-15+21=6
y=6/2=3
x=-5-3=-8.
Answer: x=-8, y=3. (-8, 3).

5) 3x+6y=6
9x-12y=18
---------------
Simplify 3x+6y=6 will get you x+2y=2,
x=2-2y,
9(2-2y)-12y=18
18-18y-12y=18
18-30y=18
30y=18-18=0
y=0/30=0
x=2-2(0)=2-0=2
Answer: x=2, y=0. (2, 0).

6) 6x+8y=26
-7x+2y=-19
-----------------
-4(-7x+2y)=-4(-19)
28x-8y=76
---------------------------
6x+8y=26
28x-8y=76
-----------------
34x=102
x=102/34=3
6(3)+8y=26
18+8y=26
8y=26-18=8
y=8/8=1
Answer: x=3, y=1. (3, 1)

BONUS:
-5x+5y=-25
3x+2y=10
---------------
Simplify -5x+5y=-25 you will get x-y=5
x=y+5
3(y+5)+2y=10
3y+15+2y=10
5y+15=10
5y=10-15=-5
y=-5/5=-1
x=-1+5=4
Answer: x=4, y=-1. (4, -1). 
6 0
2 years ago
The figure shows the layout of a symmetrical pool in a water park. What is the area of this pool rounded to the tens place? Use
k0ka [10]

Answer:

2489ft^{2}

Step-by-step explanation:

The pool are is divided into 4 separated shapes: 2 circular sections and 2 isosceles triangles. Basically, to calculate the whole area, we need to find the area of each section. Due to its symmetry, both triangles are equal, and both circular sections are also the same, so it would be enough to calculate 1 circular section and 1 triangle, then multiply it by 2.

<h3>Area of each triangle:</h3>

From the figure, we know that <em>b = 20ft </em>and <em>h = 25ft. </em>So, the area would be:

A_{t}=\frac{b.h}{2}=\frac{(20ft)(25ft)}{2}=250ft^{2}

<h3>Area of each circular section:</h3>

From the figure, we know that \alpha =2.21 radians and the radius is R=30ft. So, the are would be calculated with this formula:

A_{cs}=\frac{\pi R^{2}\alpha}{360\°}

Replacing all values:

A_{cs}=\frac{(3.14)(30ft)^{2}(2.21radians)}{6.28radians}

Remember that 360\°=6.28radians

Therefore, A_{cs}=994.5ft^{2}

Now, the total are of the figure is:

A_{total}=2A_{t}+2A{cs}=2(250ft^{2} )+2(994.5ft^{2})\\A_{total}=500ft^{2} + 1989ft^{2}=2489ft^{2}

Therefore the area of the symmetrical pool is 2489ft^{2}

3 0
3 years ago
What are the coordinates of the endpoints of the midsegment for △LMN that is parallel to LN¯¯¯¯¯ ?
Brut [27]
<span>(3, 4.5) and (3, 3)

       The midsegment of a triangle is a line connecting the midpoints of two sides of the triangle. So a triangle has 3 midsegments. Since you want the midsegment that's parallel to LN, we need to select the midpoints of LM and MN. The midpoint of a line segment is simply the average of the coordinates of each end point of the line segment. So:

   Midpoint LM:

   ((0+6)/2, (5+4)/2) = (6/2, 9/2) = (3, 4.5)

       Midpoint MN:

   ((6+0)/2, (4+2)/2) = (6/2, 6/2) = (3, 3)

       So the desired end points are (3, 4.5) and (3, 3)</span>
3 0
3 years ago
2/3 of a plot is garden.1/5 of the garden is lawn find the fraction of the plot of land that is lawn
Marina CMI [18]

Answer:

2/3 + 1/5 = 13/15

Step-by-step explanation:

5 0
3 years ago
Harriet has 3 crates of watermelons. Each crate alone weighs 15.5 pounds and contains between 32 and 36 watermelons. The weight
Anuta_ua [19.1K]

Answer:no

Step-by-step explanation: Each crate is 15.5 pounds there is only 3 crates therefor 3 crates weighing 15.5 pounds each would only weigh 46.5 pounds all together

4 0
3 years ago
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