Calculating Distance around a Polygon

Mathematics

1 answer:

RideAnS [48]3 years ago

3 0

Answer:

12.5cm

Step-by-step explanation:

Each side of the pentagonal garden has a length of 2.5 cm.

A pentagon has 5 sides.

Since the garden has congruent sides, all its lengths are equal.

Therefore:

Distance Walked by Tanya

= 5 X 2.5

=12.5cm

Tanya has walked 12.5cm in total.

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Natali [406]

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4 0

3 years ago

For which value of b can the expression x2 + bx + 18 be factored?

Dmitry_Shevchenko [17]

Answers:

b = -19
b = -11
b = -9
b = 19
b = 11
b = 9

====================================================

Explanation:

Here are all the ways to multiply to 18 when using integers only:

-1*(-18) = 18
-2*(-9) = 18
-3*(-6) = 18
1*18 = 18
2*9 = 18
3*6 = 18

Sum each pair of factors to find out a possible value of b.

-1 + (-18) = -19
-2 + (-9) = -11
-3 + (-6) = -9
1 + 18 = 19
2 + 9 = 11
3 + 6 = 9

Therefore, the possible values of b are

b = -19
b = -11
b = -9
b = 19
b = 11
b = 9

which are the final answers.

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An example:

Let's say b = 11. This would mean $x^2+bx+18$ becomes $x^2+11x+18$

It would factor to $(x+2)(x+9)$ since it was stated earlier that:

2+9 = 11

2 * 9 = 18

You can use the FOIL rule, distributive property, or the box method to confirm that $x^2+11x+18 = (x+2)(x+9)$ is a true equation for all real numbers x.

This same idea applies for the other values of b.

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

If you're curious why this works, consider multiplying the two factors (x+p) and (x+q)

Use the FOIL rule to get $(x+p)(x+q) = x^2+qx+px+pq = x^2+(p+q)x + pq$

The middle term $(p+q)x$ has the components add to the coefficient, while those same two components multiply to get the last term. This is why when factoring we're looking for two numbers that multiply to 18, and also add to the value of b (which in the case of the last example was 11).