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3 years ago

If a silver alloy that costs $6.75 an ounce is

Mathematics

1 answer:

Dmitriy789 [7]3 years ago

3 0

9514 1404 393

Answer:

88 ounces

Step-by-step explanation:

Let x represent the number of ounces of the less expensive alloy in the mix. Then the cost of the mix will be ...

6.75x +10(55) = 8(55+x)

110 = 1.25x . . . . . . subtract 440+6.75x

88 = x . . . . . . . . divide by 1.25

88 ounces of $6.75/oz silver must be used.

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Step-by-step explanation:

<em>- 7n ≤ 77</em>

n ≥ - 11

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2 years ago

How many centimeters are in 1 mile

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Answer:

1 mile = 160934 cm

Step-by-step explanation:

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3 years ago

Read 2 more answers

A bridge in the shape of an arch connects two cities separated by a river. The two ends of the bridge are located at (–7, –13) a

sdas [7]

Answer:

$y=-\dfrac{13}{49}x^2$

Step-by-step explanation:

The shape of an arch corresponds to a parabola.

the general equation for a parabola is:

$y=ax^2+bx+c$

we're given three coordinates: (-7,-13),(7,-13) and (0,0)

so we can plug these values in the general equation to make 3 separate equations:

(x,y) = (-7,-13)

$-13=a(-7)^2+b(-7)+c$

$49a-7b+c=-13$

(x,y) = (7,-13)

$-13=a(7)^2+b(7)+c$

$49a+7b+c=-13$

(x,y) = (0,0)

$0=a(0)^2+b(7)+c$

$c=0$

so we have three equations. and we can solve them simultaneously to find the values of a,b, and c.

we've already found c = 0, let's use substitute it to other equations.

$49a-7b+c=-13\quad\Rightarrow\quad49a-7b=-13$

$49a+7b+c=-13\quad\Rightarrow\quad49a+7b=-13$

we can solve these two equation using the elimination method, by simply adding the two equations

$\quad\quad49a-7b=-13\\+\quad49a+7b=-13$

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

$\quad\quad 98a=-26$

$\quad\quad a=-\dfrac{13}{49}$

Now we can plug this value of a in any of the two equations.

$49a-7b=-13$

$49\left(-\dfrac{13}{49}\right)-7b=-13$

$-13-7b=-13$

$-7b=0$

$b=0$

We have the values of a,b, and c. We can plug them in the general equation to find the equation of the arch.

$y=\left(-\dfrac{13}{49}\right)x^2+0x+0$

$y=-\dfrac{13}{49}x^2$

$49y=-13x^2$

This our equation of the arch!

5 0

3 years ago