All categories

3 years ago

If y varies directly as x, and y is 6 when x is 72, what is the value of y when x is 8?

Mathematics

2 answers:

Svetradugi [14.3K]3 years ago

5 0

Answer:

The answer is : 2/3

Step-by-step explanation:

Given is that y varies directly as x.

Means as y increases or decreases, x also increases or decreases.

When y is 6 when x is 72,

So, when x = 8, we have to find y.

We can write the relation as follows:

$\frac{6}{y}= \frac{72}{8}$

$72y=48$

$y=\frac{48}{72}$ = $\frac{2}{3}$

Eddi Din [679]3 years ago

3 0

Answer:

2/3

Step-by-step explanation:

Y varies directly as x

Y =kx

Y=6 when x = 72

First find the relationship between y and x.

i.e find the value of k

Substitute the value of x and y

6 = k *72

Make k the subject of the formula

K = 6/72

K= 1/12

:. The rlationship between x and y is

Y = 1/12x

When x is 8

Y = 1/12 * 8

Y = 8/12

Y = 2/3 and that is the answer

Hope it helped you

You might be interested in

Your family plans to start a small business in your neighborhood.Your father borrows $10,000 from the bank at an annual interest

Temka [501]

Answer:

10000*8%*3

=$2400 loan interest

4 0

3 years ago

Six identical squares are cut from the corners and edges of an 80 cm by 50 cm cardboard rectangle. the remaining piece is folded

Anna11 [10]

Check the picture.

let the length of a side of each of the squares removed be x.

The box formed will have dimensions: 80-2x, 50-2x, x(the height)

So the volume can be expressed as a function of x as follows:

f(x)=(80-2x)(50-2x)x= $[4000-160x-100x+4 x^{2} ]x=(4 x^{2}-260x+4000)x$

so $f(x)=4 x^{3}-260x^{2}+4000x$

the solutions of f'(x)=0 gives the inflection points, so the candidates for maxima points,

$f'(x)=12x^{2}-520 x +4000=0$

solving the quadratic equation, either by a calculator, graphing software, or by other algebraic methods as the discriminant formula, we find the solutions

x=10 and x=33.333

plug in f(x) these values to see which greater:

$f(10)=(80-20)(50-20)10=60*30*10=18000$ cm cubed

$f(33.333)=(80-66.666)(50-66.666)33.333=$ which is negative because (50-66.666)<0

Answer: 18000 cm cubed