Solve for X: Logarithmic Equation with x^4 Base and Multiple Terms
Question
Find X
logx421×xlogx16+4x2=7x+2
Video Solution
Solution Steps
00:00Find X
00:04Find the domain
00:10Use the formula of 1 divided by log, we'll get the inverse logarithm
00:22Use the formula for logarithm multiplication, switch between bases
00:37Solve each logarithm separately and substitute in the exercise
01:07Collect terms and arrange the equation
01:27Use the quadratic formula to find possible solutions
01:37There are always 2 solutions, addition and subtraction
01:42Check each solution with the domain
01:47And that's the solution to the question
Step-by-Step Solution
To solve this problem, we'll follow these steps:
Simplify the logarithmic expressions using properties of logarithms.
Substitute the simplifications into the original expression and simplify algebraically.
Solve the resulting equation for the variable x.
Let's work through these steps in detail:
Step 1: Simplify the logarithmic expressions.
- The expression logx421 can be rewritten using the change of base formula: logx421=4log24. This comes from recognizing that logx42=41logx2, hence logx421=4log24.
Step 2: Simplify xlogx16.
- Using the property that logx16=4logxx=4, we get xlogx16=x×4=4x.
Step 3: Substitute into the original equation.
Substituting these into the original equation logx421×xlogx16+4x2=7x+2, we get:
log24×4x+4x2=7x+2.
Step 4: Simplify and solve the equation.
- Knowing that log24×4x=2x (since log24=2), replace and simplify the equation:
2x+4x2=7x+2.
Rearrange this to: 4x2−5x−2=0.
Step 5: Solve the quadratic equation using the quadratic formula:
The quadratic formula is given by: x=2a−b±b2−4ac, where a=4, b=−5, c=−2.