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2 years ago

When solving for x, what is x squared plus 15 equals -8x

Mathematics

1 answer:

VLD [36.1K]2 years ago

5 0

Answer:

x = - 5, x = - 3

Step-by-step explanation:

Given

x² + 15 = - 8x ( add 8x to both sides )

x² + 8x + 15 = 0 ← in standard form

Consider the factors of the constant term (+ 15) which sum to give the coefficient of the x- term (+ 8)

The factors are 5 and 3, since

5 × 3 = 15 and 5 + 3= 8, thus

(x + 5)(x + 3) = 0 ← in factored form

Equate each factor to zero and solve for x

x + 5 = 0 ⇒ x = - 5

x + 3 = 0 ⇒ x = - 3

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Jane spent 3 hours exploring a mountain with a dirt bike. First, she rode 55 miles uphill. After she reached the peak she rode f

Neko [114]

Answer:

Her speed on the summit was 35 mph.

Step-by-step explanation:

Her speed on the summit was "x" mph while her speed while climbing was "x - 10" mph. The distance she rode uphill was 55 miles and on the summit it was 28 miles. The total time she explored the mountain was 3 hours. Therefore:

time uphill = distance uphill / speed uphill = 55 / (x - 10)

time summit = distance summit / speed summit = 28 / x

total time = time uphill + time summit

3 = [55 / (x - 10)] + 28 / x

3 = [55*x + 28*(x - 10)]/[x*(x - 10)]

3*x*(x - 10) = 55*x + 28*x - 280

3x² - 30*x = 83*x - 280

3x² - 113*x + 280 = 0

x1 = {-(-113) + sqrt[(-113)² - 4*(3)*(280)]}/(2*3) = 35 mph

x2 = {-(-113) - sqrt[(-113)² - 4*(3)*(280)]}/(2*3) = 2.67 mph

Since her speed on the uphill couldn't be negative the speed on the summit can only be 35 mph.

6 0

2 years ago

Divide: 16)160 A. 10 B. 11 C. 16 D. 26 E. 100

grin007 [14]

Answer:

Step-by-step explanation:

your welcome...............

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2 years ago

Complete the missing parts of the paragraph proof.

mariarad [96]

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2 years ago

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A fish tank is in the shape of a cube. Its volume is 125 ft 3. what is the area of one face of the tank

KiRa [710]

5*5*5=125
so answer is 5 ft

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2 years ago

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X = ? y = ? 16 45 degrees

mezya [45]

Let's put more details in the figure to better understand the problem:

Let's first recall the three main trigonometric functions:

$\text{ Sine }\theta\text{ = }\frac{\text{ Opposite Side}}{\text{ Hypotenuse}}$ $\text{ Cosine }\theta\text{ = }\frac{\text{ Adjacent Side}}{\text{ Hypotenuse}}$ $\text{ Tangent }\theta\text{ = }\frac{\text{ Opposite Side}}{\text{ Adjacent Side}}$

For x, we will be using the Cosine Function:

$\text{ Cosine }\theta\text{ = }\frac{\text{ Adjacent Side}}{\text{ Hypotenuse}}$ $Cosine(45^{\circ})\text{ = }\frac{\text{ x}}{\text{ 1}6}$ $(16)Cosine(45^{\circ})\text{ = x}$ $(16)(\frac{1}{\sqrt[]{2}})\text{ = x}$ $\text{ }\frac{16}{\sqrt[]{2}}\text{ x }\frac{\sqrt[]{2}}{\sqrt[]{2}}\text{ = }\frac{16\sqrt[]{2}}{2}$ $\text{ 8}\sqrt[]{2}\text{ = x}$

Therefore, x = 8√2.

For y, we will be using the Sine Function.

$\text{ Sine }\theta\text{ = }\frac{\text{ Opposite Side}}{\text{ Hypotenuse}}$ $\text{ Sine }(45^{\circ})\text{ = }\frac{\text{ y}}{\text{ 1}6}$ $\text{ (16)Sine }(45^{\circ})\text{ = y}$ $\text{ (16)(}\frac{1}{\sqrt[]{2}})\text{ = y}$ $\text{ }\frac{16}{\sqrt[]{2}}\text{ x }\frac{\sqrt[]{2}}{\sqrt[]{2}}\text{ = }\frac{16\sqrt[]{2}}{2}$ $\text{ 8}\sqrt[]{2}\text{ = y}$

Therefore, y = 8√2.

5 0

1 year ago