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3 years ago

This is a solving system of equations with the elimanaton method pls help

Mathematics

1 answer:

a_sh-v [17]3 years ago

8 0

Answer:

Step-by-step explanation:

$\underline{+\left\{\begin{array}{ccc}-4x+9y=9\\3x-9y=-18\end{array}\right}\qquad\text{add both sides of the equations}\\.\qquad-x=-9\qquad\text{chnge the signs}\\.\qquad\boxed{x=9}\\\\\text{Put the value of x to the first equation.}\\\\-4(9)+9y=9\\-36+9y=9\qquad\text{add 36 to both sides}\\9y=45\qquad\text{divide both sides by 9}\\\boxed{y=5}$

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A mixture of concrete is made up of sand and cement in the ratio of 5:3.How many cubic centimeters of sand is needed to make 160

bazaltina [42]

Answer: $100\ cm^3$

Step-by-step explanation:

Given

The ratio of mixture of sand and cement is 5:3

If the total volume of mixture is $160\ cm^3$

Suppose there is 5x and 3x cubic centimeter of sand and cement respectively i.e.

$\Rightarrow 5x+3x=160\\\Rightarrow 8x=160\\\Rightarrow x=20\ cm^3$

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2 years ago

Read 2 more answers

Find the volume of the solid, please

dsp73

Answer:

$V \approx=1436.8$

Step-by-step explanation:

Variables and symbols:

r = radius
V = volume
A = surface area
C = circumference
π = pi = 3.1415926535898
√ = square root

Volume of a sphere in terms of radius:

$V = \frac{4}{3}\pi r^3$ , $V \approx 4.1888r^3$

To calculate the volume of a sphere:

Usually the hardest part is measuring or estimating the diameter of the sphere. Special tools exist for smaller parts like balls in ball-bearings, but it gets more complicated if the size is large. Knowing that the diameter is the largest internal measurement you can take should help.

Once you have the measurement, to find the volume use the formula above, in which π is the well-known mathematical constant equal to about 3.14159. To adjust for a half-sphere calculation, just divide the result by two.

Spheres and half-spheres are useful in engineering and architecture due to their property of being able to take equal amounts of pressure or force from each direction.

Solution:

$V=\frac{4}{3} \pi r^{3} =\frac{4}{3} *\pi *7^{3} \approx1436.75504$