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3 years ago

Solve the system of linear equations by elimination 2x+7y=1 2x-4y=12

1 answer:

3 0

$\left\{\begin{array}{ccc}2x+7y=1\\2x-4y=12&\text{change the signs}\end{array}\right\\\\\underline{+\left\{\begin{array}{ccc}2x+7y=1\\-2x+4y=-12\end{array}\right}\qquad\text{add both sides of equations}\\.\qquad\qquad11y=-11\qquad\text{divide both sides by 11}\\.\qquad\qquad \boxed{y=-1}\\\\\text{Put the value of y to the first equation:}\\\\2x+7(-1)=1\\2x-7=1\qquad\text{add 7 to both sides}\\2x=8\qquad\text{divide both sides by 2}\\\boxed{x=4}\\\\Answer:\ \boxed{x=4\ and\ y=-1\to(4,\ -1)}$

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Urgent answer needed pls

worty [1.4K]

Answer:

48 cm²

Step-by-step explanation:

PTRS is parallelogram with the base length= 8cm and the height as same as the height of ∆SUR.

the height = 2×24/8 = 6cm

so, the area of PTRS= 8×6 = 48 cm²

6 0

3 years ago

Fifteen times the square of a non-zero number is equal to 20 times number.What is the number? Its not 4/3

e-lub [12.9K]

The number is (2√3) / 3

To find the missing number, convert what it says in words to an equation:
$15 {x}^{2} = 20x$
Divide both sides by 15:
${x}^{2} = \frac{20}{15} \\ \\ {x}^{2} = \frac{4}{3}$
Take the square root:
$x = \sqrt{ \frac{4}{3} } \\ \\ x = \frac{2}{ \sqrt{3} } \\ \\ x = \frac{2 \sqrt{3} }{3}$

4 0

3 years ago

What percentage is 285 feet of an acre

Aleksandr-060686 [28]

Since there are 43560 feet in an acre, 285 feet is 0.654% of an acre.
Hope this helps!

6 0

3 years ago

Read 2 more answers

given the line AB with A(1,4) and B(-3,-1) is parallel to line CD with C(8,3) and D(x,-7), solve for the missing value of x.

umka2103 [35]

Answer:

x = 0

Step-by-step explanation:

We can find the missing value by solving for the other points (graphically or algebraically). We would first find the line of Points A and B in order to find the parallel line that would help us find the coordinate point with the x-value.

1) Graph points A, B, and C.

2) Calculate the slope of points A and B by using the slope formula:

y2 - y1/x2 - x1.

-1 - 4/-3 - 1....The slope is 5/4.

3) Write 4 = 5/4(x) + b

**We get 4 from the point A (1, 4)

Plug 1 into x and solve for 4 in order to get your y-intercept.

4 = 5/4(1) + b

4 = 5/4 +b

**If 1 = 4/4, then 4 = 16/4.

16/4 = 5/4 + b

11/4 = b

2.75 = b

4) So our y-intercept is 2.75. We now have an equation of y = 5/4x + 2.75 (graph it along with points A and B to see that it intersect both points.

5) Now we will use that line to find a line parallel to it. We know that if two lines have the same slope then they are parallel, so for the equation of the parallel line, we write: y = 5/4x + b so far.

6) We will find the y-intercept and use that to find the x-value of point D.

First we plug in the x and y values of point C to find the y-intercept

y = 5/4x + b --> 3 = 5/4(8) + b --> 3 = 40/4 + b --> 3 = 10 + b --> -7 = b

7) Now we have the equation of the line that is parallel to line AB: y = 5/4x -7

To find the missing value of x, plug the y-value of point D into the equation and solve for x.

--> -7 = 5/4x -7

--> x = 0

**You can double check this by graphing each point and both equations for the lines.

8 0

2 years ago

Find the values of a and b. The diagram is not to scale. Its not c

OlgaM077 [116]

Answer:

Option A is correct : . a=115, b=71

Step-by-step explanation:

Consider the attached file.

AB is parallel to CD.

∠1+ a° = 180° (since sum of linear pairs is 180°) ---(A)

And ∠1 = ∠2 because they are corresponding angles.

∠1 = ∠2 = 65°

Putting this value in (A)

⇒65°+ a° = 180°

⇒a° = 180°-65°

⇒a° = 115°

∠3+ 109° = 180°(since sum of linear pairs is 180°) ---(B)

⇒∠3 = 180°-109°

⇒∠3 = 71°

Now, ∠3 = b° (because they are corresponding angles and corresponding angles are equal)

⇒∠3= b°= 71°

Thus Option A is correct : . a=115, b=71

7 0

3 years ago

Read 2 more answers