Math anyone??

Question

y varies directly with the square of x. If y=36 and x=2, find the value of x when y=15.



Rewrite each equation in radical form.
25x^1/2

8a^1/3


Solve each system using addition and subtraction or substitution.

2c-d=7
d=3c-11


3x-5y=9
-x+4y=-10


If you can show me the steps and explain how to do these that would be much appreciated! Thax!!

Answer 1

the first one:the square root of 25 x or 5 root x.
2:the third root of 8a or 2 third root x
3:solve the top equation for d then set the 2 equations equal to each other and solve for c. once you find c plug it back into one of the original equations to solve for d.
4: solve both equations for x then set them equal to each other and do the same thing as you did in nubmer 3.

Answer 2

This is obvious homework.

Think about this question:

If we do your homework, who will help you during test time?

I will do one question only.

We have this:

y varies directly with the square of x. If y=36 and x=2, find the value of x when y=15.

The phrase "the square of x" means x squared or x^2.

When two variable quantities have a constant (unchanged) ratio, their relationship is called a direct variation.
It is said that one variable "varies directly" as the other.

The constant ratio is called the constant of variation.

The formula for direct variation is y = k times x,
where k is the constant of variation.
"y varies directly as x"
Solving for k: k = (y/x), where (y = numerator; x = denominator)

However, for your question, it reads "y varies directly with the square of x."

y/x^2 =

36/2^2 = 15/x^2

We cross multiply and solve for x^2.

15 x 4 = 36 times x^2

60 = 36x^2

Divide both sides by 36.

60/36 = x^2

Take the square root of both sides of the equation.

Doing do and rationalizing the denominator, we get this:

x = sqrt{15}/3

Guido

Answer 3

y=36 and x=2

y=15 x= 5/3

5 root of x sqrt of 25x^1
2 cube root of a cube root of 8a ^1

2c-d=7
d=3c-11
2c-(3c+11)=7
-c+11=7
-c=-4
c=4

d=3(4)-11
d=1

3x-5y=9
-x+4y=-10

-x=-4y-10 divide by -1
x=4y+10
3(4y+10)-5y=9
12y+30-5y=9
7y+30-30=9-30
7y=-21
y=-3

-x+4(-3)=10
-x+-12=-10
-x-12+12=-10+12
-x=2
x=-2