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3 years ago

Solve by using elimination.express answer as an ordered pair 2x-5y=-7 5x-3y=11

1 answer:

8 0

$2x-5y=-7 \ \ \ \ \ \ |\times (-5) \\
5x-3y=11 \ \ \ \ \ \ \ |\times 2 \\ \\
-10x+25y=35 \\
\underline{10x-6y=22 \ \ \ \ \ \ } \\
25y-6y=35+22 \\
19y=57 \\
y=\frac{57}{19} \\
y=3 \\ \\
2x-5y=-7 \\
2x-5 \times 3 =-7 \\
2x-15=-7 \\
2x=-7+15 \\
2x=8 \\
x=\frac{8}{2} \\
x=4 \\ \\ \boxed{(x,y)=(4,3)}$

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Dmitri buys 23 pound of mixed nuts, 12 pound of chocolate

timofeeve [1]

Answer:

c. 13.20

Step-by-step explanation:

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3 years ago

john's dad gave him 8 3/4 pieces of wood. he used 4 2/3 pieces to make a bird house. his friend david then asked for 1 1/2 piece

Serjik [45]

Ok so this all about subtracting fractions this is what you want to do:

you can change 8 3/4 and 4 2/3 to have the same value and deominator
8 3/4 = 8 9/12(multiply both sides by 3)
4 2/3 = 4 8/12(multiply both sides by 4)
you do this because 12 is divisible by 3 and 4

then, subtract 4 8/12 from 8 9/12 because John is using some of the wood his dad gave him.
then subtract once again, taking 11/2 away from your difference.
again match the deominator of 11/2 to the deominator of your difference which should be 12. another divisible of 12 is 2 and 6.
11/2 = 66/12 = 5 6/12(multiply both the top and bottom by 6)
and start subtracting.

so John should have -1 5/12(?) wood left

3 0

3 years ago

It takes 32 hours for a motorboat moving downriver to get from pier A to pier B. The return journey takes 48 hours. How long doe

lina2011 [118]

Answer:

Time taken by the un powered raft to cover this distance is T = 192.12 hr

Step-by-step explanation:

Let speed of boat = u $\frac{km}{hr}$

Speed of current = v $\frac{km}{hr}$

Let distance between A & B = 100 km

Time taken in downstream = 32 hours

$32 = \frac{100}{u +v}$

$u + v = \frac{100}{32}$

u + v = 3.125 ------ (1)

Time taken in upstream = 48 hours

$48 = \frac{100}{u -v}$

$u -v = \frac{100}{48}$

u - v = 2.084 ------- (2)

By solving equation (1) & (2)

u = 2.6045 $\frac{km}{hr}$

v = 0.5205 $\frac{km}{hr}$

Now the time taken by the un powered raft to cover this distance

$T = \frac{100}{v}$

Because un powered raft travel with the speed of the current.

$T = \frac{100}{0.5205}$

T = 192.12 hr

Therefore the time taken by the un powered raft to cover this distance is

T = 192.12 hr

3 0

4 years ago

Read 2 more answers

The hypotenuse of a right angled triangle is 2√13 cm . If the smaller side is increased by 2 cm and the larger side is increased

White raven [17]

Statement:

The hypotenuse of a right angled triangle is 2√13 cm. If the smaller side is increased by 2 cm and the larger side is increased by 3 cm, the new hypotenuse will be √117 cm.

To find out:

The length of the larger side of the right angled triangle.

Solution:

Let us consider x as the smaller side and y as the larger side.

Then, in the right angled triangle,

x² + y² = (2√13)² ...(I) [By Pythagoras Theorem]

Now, if the smaller side is increased by 2 cm, then the smaller side will be (x + 2).

And if the larger side is increased by 3 cm, then the larger side will be (y + 3).

Then, in the new right angled triangle,

(x + 2)² + (y + 3)² = (√117)² [By Pythagoras Theorem]

or, x² + 2 × 2 × x + 2² + y² + 2 × 3 × y + 3² = (√117)²

or, x² + 4x + 4 + y² + 6y + 9 = (√117)²

or, x² + y² + 4x + 6y + 13 = (√117)²

Now, put the value of x² + y² from equation (I),

or, (2√13)² + 4x + 6y + 13 = (√117)²

or, (2 × 2 × √13 × √13) + 4x + 6y + 13 = (√117 × √117)

or, 52 + 4x + 6y + 13 = 117

or, 4x + 6y = 117 - 52 - 13

or, 4x + 6y = 52

or, 4x = 52 - 6y

or, x = $\frac {(52 - 6y)}{4}$ ...(II)

Now, put the value of x of equation (II) in (I),

x² + y² = (2√13)²

or, $\frac {(2704-624y +36y²)}{16}$ + y² = 52

or, $\frac {(2704-624y +36y² + 16y²)}{16}$ = 52

or, 52y²-624y + 2704 = 52 × 16

or, 52y² - 624y + 2704 - 832 = 0

or, 52y² - 624y + 1872 = 0

or, 52(y² - 12y + 36) = 0

or, y²-12y +36 = 0 ÷ 52

or, y²-12y +36 = 0

or, (y)² - 2 × 6 × y + (6)² = 0

or, (y - 6)² = 0

or, y - 6=0

or, y = 6

We have taken y as the length of the larger side of the right angled triangle.

So, the length of the larger side is 6 cm.

Answer:

6 cm

Hope you could understand.

If you have any query, feel free to ask.

6 0

3 years ago

Which shape is both rectangle and a square?

mina [271]

Step-by-step explanation:

the rhombus is both rectangle and square

8 0

2 years ago

Read 2 more answers