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3 years ago

(x-9)(x+9) find the product

Mathematics

1 answer:

klio [65]3 years ago

7 0

Method 1.

Use $(a-b)(a+b)=a^2-b^2$

$(x-9)(x+9)=x^2-9^2=x^2-81$

Method 2.

Use distributive property: (a + b)(c + d) = ac + ad + bc + bd

$(x-9)(x+9)=(x)(x)+(x)(9)+(-9)(x)+(-9)(9)=x^2+9x-9x-81=x^2-81$

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3 years ago

The volume of ice-cream in the cone is half the volume of the cone. The cone has a 3 cm radius and

zhannawk [14.2K]

Answer:

h = 5 cm

Step-by-step explanation:

Given that,

The volume of ice-cream in the cone is half the volume of the cone.

Volume of cone is given by :

$V_c=\dfrac{1}{3}\pi r^2h$

r is radius of cone, r = 3 cm

h is height of cone, h = 6 cm

So,

$V_c=\dfrac{1}{3}\pi (3)^2\times 6\\\\V_c=18\pi\ cm^3$

Let $V_i$ is the volume of icecream in the cone. So,

$V_i=\dfrac{18\pi}{2}=9\pi\ cm^3$

Let H be the depth of the icecream.

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$\dfrac{H}{6}=\dfrac{r}{3}\\\\r=\dfrac{H}{2}$

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4 years ago

What does 5/7c=13/14 equal

natita [175]

To find c, you must isolate it.
To do this, you must divide both sides by 5/7, since that is being multiplied by c and you must do the inverse to it to cancel it out in order to leave c by itself.

5/7c ÷ 5/7 = c

13/14 ÷ 5/7
To divide fractions, follow these steps:
Step 1- Turn the second fraction, 5/7 in this case, into its reciprocal. This means swapping the places of the numerator and denominator.
5/7 reciprocal = 7/5

Step 2- multiply the original first fraction and reciprocal second fraction.
13/14 • 7/5
13 • 7 = 91
14 • 5 = 70
13/14 ÷ 5/7 = 91/70

Step 3- Simplify if possible.
91/70
Since 70 can go into 90, you can turn this into a mixed number.
1 and 21/70
Now simplify 21/70.
Both can be divided by 7.
21 ÷ 7 = 3
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So simplified, 91/70 equals 1 and 3/10.
As a decimal, this is 1.3.

So the answer is c = 1.3, or 1 and 3/10.

Hope this helps :)

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4 years ago