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3 years ago

Solve by elimination -3x+2y=10 -2x-y=-5

1 answer:

6 0

First you need to get two similar terms to eliminate, I'll do y:
-3x + 2y = 10
-4x - 2y= -10
And then you minus
x = 20
Now you can substitute x in to one of the equations to find y:
-60 + 2y = 10
+ 60
2y = 70
÷ 2
y = 35
So your values are y = 35 and x = 20. Hope this helps!

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Sally paid the following bills rent $450.00 cell phone $37.50 and cable $69.99 how much money did she pay ?

romanna [79]

Answer:

557.49

Step-by-step explanation:

Add the three bills together

450.00

37.50

69.99

--------------

557.49

3 0

3 years ago

The table shows the number of pounds of green

mel-nik [20]

Answer:

10 1/2

Step-by-step explanation:

First you would do.

9+2/3+5/6

2/3=4/6

9+4/6+5/6

9+9/6=3/2

9+1 1/2

=10 1/2

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3 years ago

Determine all prime numbers a, b and c for which the expression a ^ 2 + b ^ 2 + c ^ 2 - 1 is a perfect square .

kogti [31]

Answer:

The family of all prime numbers such that $a^{2} + b^{2} + c^{2} -1$ is a perfect square is represented by the following solution:

$a$ is an arbitrary prime number. (1)

$b = \sqrt{1 + 2\cdot a \cdot c}$ (2)

$c$ is another arbitrary prime number. (3)

Step-by-step explanation:

From Algebra we know that a second order polynomial is a perfect square if and only if $(x+y)^{2} = x^{2} + 2\cdot x\cdot y + y^{2}$ . From statement, we must fulfill the following identity:

$a^{2} + b^{2} + c^{2} - 1 = x^{2} + 2\cdot x\cdot y + y^{2}$

By Associative and Commutative properties, we can reorganize the expression as follows:

$a^{2} + (b^{2}-1) + c^{2} = x^{2} + 2\cdot x \cdot y + y^{2}$ (1)

Then, we have the following system of equations:

$x = a$ (2)

$(b^{2}-1) = 2\cdot x\cdot y$ (3)

$y = c$ (4)

By (2) and (4) in (3), we have the following expression:

$(b^{2} - 1) = 2\cdot a \cdot c$

$b^{2} = 1 + 2\cdot a \cdot c$

$b = \sqrt{1 + 2\cdot a\cdot c}$

From Number Theory, we remember that a number is prime if and only if is divisible both by 1 and by itself. Then, $a, b, c > 1$ . If $a$ , $b$ and $c$ are prime numbers, then $2\cdot a\cdot c$ must be an even composite number, which means that $a$ and $c$ can be either both odd numbers or a even number and a odd number. In the family of prime numbers, the only even number is 2.

In addition, $b$ must be a natural number, which means that:

$1 + 2\cdot a\cdot c \ge 4$

$2\cdot a \cdot c \ge 3$

$a\cdot c \ge \frac{3}{2}$

But the lowest possible product made by two prime numbers is $2^{2} = 4$ . Hence, $a\cdot c \ge 4$ .

The family of all prime numbers such that $a^{2} + b^{2} + c^{2} -1$ is a perfect square is represented by the following solution:

$a$ is an arbitrary prime number. (1)

$b = \sqrt{1 + 2\cdot a \cdot c}$ (2)

$c$ is another arbitrary prime number. (3)

Example: $a = 2$ , $c = 2$

$b = \sqrt{1 + 2\cdot (2)\cdot (2)}$

$b = 3$

4 0

3 years ago

A coordinate map of the local grocery store is shown below. Ice cream is located at the point (-8,0)(−8,0)left parenthesis, minu

Alona [7]

Answer:

Step-by-step explanation:

If on the coordinate map, ice cream is located at the point (-8,0) and sprinkles are located at the point (-8,6), we can find the distance between the coordinate points using the formula;

D = √(x2-x1)²+(y2-y1)²

Given

x1 = -8, y1 = 0, x2 = -8 and y2 = 6

Substitute

D = √(x2-x1)²+(y2-y1)²

D = √(-8-(-8))²+(6-0)²

D = √0²+6²

D = √36

D = 6units

Hence the distance between the coordinate points is 6units

7 0

3 years ago

Let n be the number of couples dancing in a competition. If there are 5 organizers, which expression represents the total number

Korvikt [17]

2n+5...a couple is two people so you need to multiply the number of couples, n, by 2 to get the total number of dancers. Then add the total number of organizers.

3 0

3 years ago