log48log4(x2+8x+1)=2
x=?
To solve the problem, we'll follow these steps:
- Step 1: Simplify the given expression using logarithmic identities.
- Step 2: Solve the resulting quadratic equation for x.
Now, let's work through each step:
Step 1: We start with the equation:
log48log4(x2+8x+1)=2
We know that log48=23, since 8=43/2. Thus, we can rewrite the equation as:
log4(x2+8x+1)=2×23=3
Applying the property of logarithms that states logba=c⇒a=bc, we have:
x2+8x+1=43=64
Step 2: Solve the resulting quadratic equation:
x2+8x+1=64
Subtract 64 from both sides to bring the equation to standard form:
x2+8x+1−64=0
x2+8x−63=0
Now, apply the quadratic formula, x=2a−b±b2−4ac, where a=1, b=8, and c=−63:
x=2⋅1−8±82−4⋅1⋅(−63)
x=2−8±64+252
x=2−8±316
Simplify 316 as 79⋅4=279:
x=2−8±279
Thus, x=−4±79.
Therefore, the solution to the equation is x=−4±79.
−4±79