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3 years ago

Select the step in the solution that shows the first error.

Mathematics

1 answer:

siniylev [52]3 years ago

8 0

Answer:

Step 2: 20x = 80 + 10x

Step-by-step explanation:

Step 1: 20x - 10 = 80 + 10x

Add 10 to each side

20x - 10+10 = 80+10 + 10x

20x = 90 + 10x

Step 2: 20x = 80 + 10x This has the first error

Step 3: 10x = 80

Step 4: x= 8

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Find a4 for the arithmetic series with S4=-36 and a1=9

erastova [34]

ANSWER

The 4th term is -27

EXPLANATION

The sum of the first n-terms of an arithmetic sequence is

$S_n= \frac{n}{2} (2a_1+d(n-1))$

It was given that,

$S_4 = - 36$

$a_1 = 9$

$- 36= \frac{ 4}{2} (2 \times 9+d(4-1))$

$-36=2(18+3d)$

$-18=18+3d$

$-18 - 18 = 3d$

$3d = - 36$

$d = - 12$

The n-term is given by:

$a_n=a_1+ (n-1)d$

We substitute n=4 to get,

$a_4=9+ (4-1) \times -12$

$a_4=9+ 3\times -12$

$a_4=9 - 36$

$a_4= - 27$

5 0

3 years ago

The distance between my house and the school is 25 miles and it takes 10min by bus. How fast is the bus traveling?

Vlad1618 [11]

Answer:

2.5 miles per minute

Step-by-step explanation:

speed = distance ÷ time

speed = s

distance = 25 miles

time = 10 minutes

s = 25÷10

s = 2.5 miles per minute

5 0

3 years ago

A pair of numbers whose sum is zero?

ipn [44]

1 and negative 1. Any number plus the opposite (negative) version of itself works. Hope this helped, could I possibly get brainliest?

7 0

3 years ago

Read 2 more answers

What is the quadratic formula in vertex form?

telo118 [61]

Answer:

See explanation below to use the vertex form to solve a quadratic equation.

Step-by-step explanation:

(x - h)^2 - k = 0, the vertex is (h, -k)

An example below, taking a quadratic equation and completing the square:

x^2 - 2x - 1 = 0

x^2 - 2x = 1

(-2/-2)^2 = 1, add 1 to both sides of the equation.

x^2 - 2x + 1 = 1 + 1

(x - 1)^2 = 2

(x - 1)^2 - 2 = 0

The vertex is (1, -2)

8 0

3 years ago

Let ℓ be the tangent line to the curve y = 2x³ at the point (1, 2). The angle of inclination of ℓ is the angle ϕ that ℓ makes wi

Scorpion4ik [409]

Answer:

Approximately 83 degrees

Step-by-step explanation:

Consider the curve

$y=2x^3\\$

Let us find equation of tangent or slope of tangent at (1,2)

Differentiate y wrt x

$y' = 8x^2$

slope of tangent = value of derivative at that point

So slope of tangent at (1,2) = $8(1^2) = 8$

Slope of a line is nothing but tangent of the angle it makes with positive x axis

So if phi is the angle

we have

$tan \phi =8\\\phi = arctan 8\\= 82.875$

Approximately 83 degrees

3 0

3 years ago