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marta [7]
2 years ago
9

PLEASE HELP I WILL MARK YOU BRAINIEST!!

Mathematics
1 answer:
Keith_Richards [23]2 years ago
5 0
Answer:
r = 9

The error happened when -3 was multiplied by -r in the first step, negative and negative makes a positive so it should have been
-18 + 3r= 9 in the second step.
Hope this helps :)
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What fraction is not equivalent to 36/60
Andreyy89
Fractions that aren't equivalent would be 30/60, 34/60 and anything that cannot be the same as 36/60.
3 0
3 years ago
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There are 16 competitors in the MATHCOUNTS Trainer competition, including 3 from Vienna. The gold medal goes to first place, sil
Brums [2.3K]

Answer:

1404

Step-by-step explanation:

13*12*9

5 0
2 years ago
Please help me with these. These are so hard.<br><br>​
LuckyWell [14K]

\bf \textit{difference and sum of cubes} \\\\ a^3+b^3 = (a+b)(a^2-ab+b^2) ~\hfill a^3-b^3 = (a-b)(a^2+ab+b^2) \\\\[-0.35em] \rule{34em}{0.25pt}\\\\ \boxed{a^6+b^6}\implies a^{2\cdot 3}+b^{2\cdot 3}\implies (a^2)^3+(b^2)^3 \\[2em] [a^2+b^2] [(a^2)^2-a^2b^2+(b^2)^2]\implies \boxed{(a^2+b^2)(a^4-a^2b^2+b^4)}

about the second one... well, is a "fait accompli" that using the pythagorean theorem, if x = 8 and y = 5, the hypotenuse must be √(8² + 5²) = √(89), which is neither of those choices.

5, 8, 13 are no dice, namely 5² + 8² ≠ 13

25, 64, 17 is are no dice too, because 25² + 17² ≠ 64²

however, 5,12 and 13 are indeed a pythagorean triple

also is 39, 80, 89.

when looking for a pythagorean triple, recall that c² = a² + b².

so the longest leg is the sum of the square of the small ones.

so what you'd do is, check the small legs, square them, add them up, if they're indeed a pythagorean triple, they "must" add up to the longest leg.

4 0
3 years ago
Substitute the values for a, b, and c into b2 – 4ac to determine the discriminant. Which quadratic equations will have two real
hoa [83]

Answer: 0=2x^2-7x-9\\0=4x^2-3x-1\\0=x^2-2x-8


Step-by-step explanation:

We know that the standard quadratic equation is  ax^2+bx+c=0

Let's compare all the given equation to it and , find discriminant.

1. a=2, b= -7, c=-9

b^2-4ac=(-7)^2-4(2)(-9)=49+72>0

So it has 2 real number solutions.

2. a=1, b=-4, c=4

b^2-4ac=(-4)^2-4(1)(4)=16-16=0

So it has only 1 real number solution.

3. a=4, b=-3, c=-1

b^2-4ac=(-3)^2-4(4)(-1)=9+16=25>0

So it has 2 real number solutions.

4. a=1, b=-2, c=-8

b^2-4ac=(-2)^2-4(1)(-8)=4+32=36>0

So it has 2 real number solutions.

5. a=3, b=5, c=3

b^2-4ac=(5)^2-4(3)(3)=25-36=-9

Thus it does not has real solutions.



5 0
3 years ago
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barxatty [35]

25/250 = 1/10

I do not know that much english. I an spanish so I might have done it wrong.

8 0
3 years ago
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