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1 year ago

Example Solve the quadratic equation x² - 6x +13=0

1 answer:

8 0

$x^2-6x+13=0\\\\\implies x^2-6x =-13\\\\\implies x^2 -2\cdot 3 \cdot x+3^2 -3^2 =-13\\\\\implies (x-3)^2 -9 = -13\\\\\implies (x-3)^2 = -13 +9 = -4\\\\ \implies x-3 =\pm\sqrt{-4} \\\\\implies x -3 = \pm2i\\\\\implies x = \pm 2i +3\\\\\text{Hence,}~ x = 3 + 2i, ~~ x = 3-2i$

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Answer:

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Step-by-step explanation:

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2 years ago

A basketball player shoots a basketball that reaches a height above 15 feet before landing back on the ground exactly after 7 se

Papessa [141]

Answer:

I and IV

Step-by-step explanation:

Since the height of the basketball reaches above 15 feet, hence the maximum of the function should be greater than 15 feet. Also at 7 seconds, the ball is on the ground, hence f(7) = 0 feet

The maximum of a function is at x = -b/2a

i) f(x) = -(x-3)² + 16 = -(x² - 6x + 9) + 16 = -x² + 6x + 7

The maximum of a function is at x = -b/2a = -6 / 2(-1) = 3

f(3) = -(3-3)² + 16 = 16 > 15

Also f(7) = - (7 - 3)² + 16 = 0

Hence this option is correct

ii) f(x) = -x² + 8x - 7

The maximum of a function is at x = -b/2a = -8 / 2(-1) = 4

f(4) = -4² + 8(4) - 7 = 9 < 15 not correct

Also f(7) = - 7² + 8(7) - 7 = 0

Hence this option is not correct since the maximum f(4) = 9 < 15

iii) f(x) = -(x-3)² + 14 = -(x² - 6x + 9) + 14 = -x² + 6x + 5

The maximum of a function is at x = -b/2a = -6 / 2(-1) = 3

f(3) = -(3-3)² + 14 = 14 < 15

Also f(7) = - (7 - 3)² + 14 = -2

Hence this option is not correct since the maximum f(4) = 9 < 15 and f(7) ≠ 0

iv)f(x) = -x² + 6x + 7

The maximum of a function is at x = -b/2a = -6 / 2(-1) = 3

f(3) = -(3)² + 6(3) + 7 = 16 > 15

Also f(7) = - (7)² + 6(7) + 7 = 0

Hence this option is correct

3 0

2 years ago

which of the following is equivalent to 3 sqrt 32x^3y^6 / 3 sqrt 2x^9y^2 where x is greater than or equal to 0 and y is greater

Nutka1998 [239]

Answer:

$\frac{\sqrt[3]{16y^4}}{x^2}$

Step-by-step explanation:

The options are missing; However, I'll simplify the given expression.

Given

$\frac{\sqrt[3]{32x^3y^6}}{\sqrt[3]{2x^9y^2} }$

Required

Write Equivalent Expression

To solve this expression, we'll make use of laws of indices throughout.

From laws of indices $\sqrt[n]{a} = a^{\frac{1}{n}}$

So,

$\frac{\sqrt[3]{32x^3y^6}}{\sqrt[3]{2x^9y^2} }$ gives

$\frac{(32x^3y^6)^{\frac{1}{3}}}{(2x^9y^2)^\frac{1}{3}}$

Also from laws of indices

$(ab)^n = a^nb^n$

So, the above expression can be further simplified to

$\frac{(32^\frac{1}{3}x^{3*\frac{1}{3}}y^{6*\frac{1}{3}})}{(2^\frac{1}{3}x^{9*\frac{1}{3}}y^{2*\frac{1}{3}})}$

Multiply the exponents gives

$\frac{(32^\frac{1}{3}x*y^{2})}{(2^\frac{1}{3}x^{3}*y^{\frac{2}{3}})}$

Substitute $2^5$ for 32

$\frac{(2^{5*\frac{1}{3}}x*y^{2})}{(2^\frac{1}{3}x^{3}*y^{\frac{2}{3}})}$

$\frac{(2^{\frac{5}{3}}x*y^{2})}{(2^\frac{1}{3}x^{3}*y^{\frac{2}{3}})}$

From laws of indices

$\frac{a^m}{a^n} = a^{m-n}$

This law can be applied to the expression above;

$\frac{(2^{\frac{5}{3}}x*y^{2})}{(2^\frac{1}{3}x^{3}*y^{\frac{2}{3}})}$ becomes

$2^{\frac{5}{3}-\frac{1}{3}}x^{1-3}*y^{2-\frac{2}{3}}$

Solve exponents

$2^{\frac{5-1}{3}}*x^{-2}*y^{\frac{6-2}{3}}$

$2^{\frac{4}{3}}*x^{-2}*y^{\frac{4}{3}}$

From laws of indices,

$a^{-n} = \frac{1}{a^n}$ ; So,

$2^{\frac{4}{3}}*x^{-2}*y^{\frac{4}{3}}$ gives

$\frac{2^{\frac{4}{3}}*y^{\frac{4}{3}}}{x^2}$

The expression at the numerator can be combined to give

$\frac{(2y)^{\frac{4}{3}}}{x^2}$

Lastly, From laws of indices,

$a^{\frac{m}{n} = \sqrt[n]{a^m}$ ; So,

$\frac{(2y)^{\frac{4}{3}}}{x^2}$ becomes

$\frac{\sqrt[3]{(2y)}^{4}}{x^2}$

$\frac{\sqrt[3]{16y^4}}{x^2}$

Hence,

$\frac{\sqrt[3]{32x^3y^6}}{\sqrt[3]{2x^9y^2} }$ is equivalent to $\frac{\sqrt[3]{16y^4}}{x^2}$

8 0

3 years ago

Usain Bolt of Jamaica set a world record in 2009 for the 200- meter dash with a time of 19.19 seconds. What was his average spee

kirill [66]

Answer:

His average speed was of 10.42 m/s

Step-by-step explanation:

We use the following relation to solve this question:

$v = \frac{d}{t}$

In which v is the velocity(in m/s), d is the distance(in meters), and t is the time, in seconds.

Usain Bolt of Jamaica set a world record in 2009 for the 200- meter dash with a time of 19.19 seconds.

This means that $d = 200, t = 19.19$

So his average speed was of:

$v = \frac{d}{t} = \frac{200}{19.19} = 10.42$

His average speed was of 10.42 m/s

6 0

3 years ago

(HELPPP PLSSS) A group of friends goes out for lunch. The total bill, excluding tax, is $22. IF tax on the meal is 6% and if a 2

Over [174]

Answer:

22*1.06 = cost of meal with tax = 23.32

22*.20 = tip on the pre-tax cost = 4.40

Total = $27.72

Step-by-step explanation:

8 0

2 years ago

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