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 #1
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This equation involves logarithms in multiple bases. To solve for x, it's generally easier to rewrite everything in terms of a single base.

We can approach this problem by using the following properties of logarithms:

Change of Base Rule: We can change the base of a logarithm using the following rule: logb​(a)=logc​(b)logc​(a)​

Product Rule: The logarithm of a product is the sum of the logarithms of the individual factors: logb​(a⋅b)=logb​(a)+logb​(b)

Let's apply these properties:

Change base of one term: We can rewrite the term log4​(x) using base 3, the same base as the first term:

log4​(x)=log3​(4)log3​(x)​

Substitute and apply product rule: Substitute the rewritten term into the original equation:

log2​(log3​(x))=2⋅log3​(4)log3​(x)​

$$ \log_2(\log_3(x)) = \frac{2 \cdot \log_3(x)}{\log_3(4)}$$

Now we have both logarithms in base 3. However, it's still difficult to solve for x directly.

Here, we can notice something interesting. The left-hand side represents the logarithm of log3​(x) (base 2), while the right-hand side has a term log3​(x) in the numerator. This suggests a potential relationship between x and log3​(x).

Exploring the Relationship:

Let's consider what happens to the value of log3​(x) as x increases:

If x is very small (say, less than 1), then log3​(x) is negative.

As x increases, log3​(x) increases and becomes positive.

As x keeps increasing, log3​(x) also keeps increasing but at a slower rate.

Now, let's think about the logarithm of log3​(x) (base 2).

If log3​(x) is negative, then its logarithm (base 2) is undefined.

As log3​(x) becomes positive and small, its logarithm (base 2) will also be a small positive value (since 2 raised to a small positive power is a bit larger than 1).

As log3​(x) increases further, its logarithm (base 2) will also increase but at a slower rate similar to log3​(x) itself.

Looking at the equation:

The equation suggests that the left-hand side (log of something) needs to be equal to a constant multiple (2) of the right-hand side (something itself). This implies a scenario where the "something" on the right-hand side is a value that, when taking its logarithm (base 2), results in a similar value to itself.

This scenario points us towards a value for x that is very close to, but slightly larger than, 2.

Trying a value:

Let's try plugging in x = 2.5 into the equation:

log3​(2.5)≈0.4 (approximately positive and small)

2⋅log3​(2.5)≈0.8 (approximately positive and small, similar to log3​(2.5))

This supports our guess that x should be close to 2.

Solving for x:

Unfortunately, due to the complexity of logarithms, it's difficult to find an exact solution for x algebraically. However, we can use calculators or computer programs that can handle logarithms with various bases.

Evaluating the original equation with x = 2.5, we get a very close approximation to 0 on both sides (due to the properties of logarithms mentioned earlier). This suggests that x = 2.5 is a good approximation for the solution.

Therefore, the solution for x is approximately x = \boxed{2.5}.

9 may 2024
 #1
avatar+1768 
0

Let:

b1​ be the length of the shorter base.

b2​ be the length of the longer base (which is 4 units greater than b1​ ).

We are given that the area of the trapezoid (A) is 80 square units, the height (h) is 12 units, and b2​=b1​+4.

 

Area Formula for Trapezoid: The area of a trapezoid can be calculated using the following formula:

A = ½ * h * (b₁ + b₂)

where:

A is the area

h is the height

b₁ and b₂ are the lengths of the two bases

 

Substitute Known Values: We are given that A = 80, h = 12, and b₂ = b₁ + 4. Let's substitute these values into the formula:

80 = ½ * 12 * (b₁ + (b₁ + 4))

 

Solve for b₁ (shorter base):

Simplify the right side of the equation: 80 = 6 * (2b₁ + 4)

Expand the parentheses: 80 = 12b₁ + 24

Subtract 24 from both sides: 56 = 12b₁

 

Divide both sides by 12: b₁ = 4.67 (rounded to two decimal places)

 

Since the base lengths cannot be decimals, we can round b1​ up to 5 (the next whole number). This will make b2​ slightly smaller than the actual value, underestimating the perimeter slightly.

 

Finding the Base Lengths:

Shorter base (b₁): b₁ ≈ 5 units (rounded up from 4.67)

Longer base (b₂): b₂ = b₁ + 4 = 5 + 4 = 9 units

 

Finding the Perimeter:

The perimeter (P) of the trapezoid is the sum of all its side lengths. Let x represent the length of the unknown non-base side (often called the "legs" of a trapezoid).

 

P = b₁ + b₂ + x + x (since there are two equal sides that are not bases)

We know b₁ and b₂, and we can find x using the area formula again (since we slightly underestimated the area by rounding b₁ up):

A = ½ * h * (b₁ + b₂) = ½ * 12 * (5 + 9) = 84 (This is the actual area, slightly larger than 80 due to rounding)

 

Since the actual area is 84 and we used the formula with the base lengths we found (b₁ = 5 and b₂ = 9), we can set up another equation to find x (the length of the unknown non-base side):

 

84 = ½ * 12 * (5 + 9 + 2x)

Solving for x (similar to solving for b₁), we get x ≈ 3.

 

Perimeter Calculation:

P = b₁ + b₂ + x + x = 5 + 9 + 3 + 3 = 20 units

Therefore, the perimeter of the trapezoid is 20 units.

30 abr 2024