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2 years ago

How to solve the exponential equation for 3^k2 • 3^-k+2 = 81

Mathematics

1 answer:

wariber [46]2 years ago

6 0

Answer:

k=2

Step-by-step explanation:

3^k*2 * 3^-k+2 = 81

Factor out 81 to be : 3^4

Rewrite the equation:

k*2 - k+2 = 4

k^2 - 2k = 4

Simplify : k+2 = 4

- 2 - 2

k = 2

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Nostrana [21]

Answer:

$\displaystyle \begin{cases} \displaystyle {x} _{1} = - p \\ \displaystyle x _{2} = - q \end{cases}$

Step-by-step explanation:

we would like to solve the following equation for x:

$\displaystyle \frac{1}{p} + \frac{1}{q} + \frac{1}{x} = \frac{1}{p + q + x}$

to do so isolate $\frac{1}{x}$ to right hand side and change its sign which yields:

$\displaystyle \frac{1}{p} + \frac{1}{q} = \frac{1}{p + q + x} - \frac{1}{x}$

simplify Substraction:

$\displaystyle \frac{1}{p} + \frac{1}{q} = \frac{x - (q + p + x)}{x(p + q + x)}$

get rid of only x:

$\displaystyle \frac{1}{p} + \frac{1}{q} = \frac{ - (q + p )}{x(p + q + x)}$

simplify addition of the left hand side:

$\displaystyle \frac{q + p}{pq} = \frac{ - (q + p )}{x(p + q + x)}$

divide both sides by q+p Which yields:

$\displaystyle \frac{1}{pq} = \frac{ -1}{x(p + q + x)}$

cross multiplication:

$\displaystyle x(p + q + x) = - pq$

distribute:

$\displaystyle xp + xq + {x}^{2} = - pq$

isolate -pq to the left hand side and change its sign:

$\displaystyle xp + xq + {x}^{2} + pq = 0$

rearrange it to standard form:

$\displaystyle {x}^{2} + xp + xq + pq = 0$

now notice we end up with a quadratic equation therefore to solve so we can consider factoring method to use so

factor out x:

$\displaystyle x( {x}^{} + p ) + xq + pq = 0$

factor out q:

$\displaystyle x( {x}^{} + p ) +q (x + p)= 0$

group:

$\displaystyle ( {x}^{} + p ) (x + q)= 0$

by Zero product property we obtain:

$\displaystyle \begin{cases} \displaystyle {x}^{} + p = 0 \\ \displaystyle x + q= 0 \end{cases}$

cancel out p from the first equation and q from the second equation which yields:

$\displaystyle \begin{cases} \displaystyle {x}^{} = - p \\ \displaystyle x = - q \end{cases}$

and we are done!

3 0

2 years ago

Need help... help me

elena-s [515]

It’s 270 I believe good luck tho

5 0

2 years ago

Ava has a bag with 3 red, 2 blue, and 11 green beads.

vlada-n [284]

Answer:

5/16 or 31.25%

Step-by-step explanation:

There are 16 beads altogether 11 are green and the rest aren't so there for is 5 out of 16 chance green won't be selected

8 0

2 years ago

Read 2 more answers

Evaluate the expression w2 - v + 1 for w = -2 and v = -8.

chubhunter [2.5K]

Plug in the value of -2 and -8

(-2)^2 - (-8) + 1

4 + 8 + 1 = 13

8 0

3 years ago

Read 2 more answers

Classify each of the following as rational or irrational:

Gemiola [76]

Answer:

Rational:-5, 2/3, 0.5, sqrt 16

Irrational: sqrt 11, pi

Step-by-step explanation:

A rational number is a number which can be represented as a ratio or fraction and whose decimal is terminating or repeating. This includes all whole numbers positive and negative too.

Ex. -5, 2/3, 0.5, sqrt 16

An irrational number is a number that CANNOT be represented as a ratio or fraction and whose decimal is NOT terminating or repeating. These often include square roots and numbers like pi.

Ex. sqrt 11, pi

7 0

2 years ago