What are the next three terms of 1,-2,4

Next three terms are -8, 16 and -32

Step-by-step explanation:

We are given the sequence:-

1, -2, 4, ...

We want to find next three terms:-

1, -2, 4, a4, a5, a6, ...

Since the sequence is geometric because it has common ratio;-

-2/1 = -2

4/-2 = -2

Our common ratio is -2.

General Term of Geometric

Our first term or a1 is 1

Our common ratio or r is -2

Therefore:-

Since we want to find next three terms which are a4,a5 and a6. Substitute n = 4,5 and 6 in.

Finding a4

Finding a5

Finding a6

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step-by-step explanation:

(b) 240

step-by-step explanation:

first, we use the pythagorean formula using the given side lengths to find x. then we use x to find the side lengths. then we add the side lengths to find the perimeter.

pythagorean theorem formula:

a^2 + b^2 = c^2

(x - 20)^2 + (x - 40)^2 = x^2

x^2 - 40x + 400 + x^2 - 80x + 1600 = x^2

x^2 -120x + 2000 = 0

(x - 100)(x - 20) = 0

x - 100 = 0 or x - 20 = 0

x = 100 or x = 20

we see that the solution x = 20 must be discarded because it will give a negative side length and a side length of 0. the only valid solution is x = 100.

perimeter = sum of the lengths of the sides

perimeter = x + x - 20 + x - 40

perimeter = 3x - 60

replace x with 100.

perimeter = 3(100) - 60

perimeter = 300 - 60

perimeter = 240