The problem consists of three sub-problems: (a) Solve the exponential equation $8^{-x^2 + x} = 2^{5x-1}$. (b) Solve the logarithmic equation $log_a(2p+1) + log_a(3p-10) = log_a(11p)$ for $p>0$. (c) Solve the logarithmic equation $log_2(x) - 3 + log_2(x+3) = 0$.

AlgebraExponential EquationsLogarithmic EquationsQuadratic EquationsLogarithm PropertiesEquation Solving
2025/6/4

1. Problem Description

The problem consists of three sub-problems:
(a) Solve the exponential equation 8x2+x=25x18^{-x^2 + x} = 2^{5x-1}.
(b) Solve the logarithmic equation loga(2p+1)+loga(3p10)=loga(11p)log_a(2p+1) + log_a(3p-10) = log_a(11p) for p>0p>0.
(c) Solve the logarithmic equation log2(x)3+log2(x+3)=0log_2(x) - 3 + log_2(x+3) = 0.

2. Solution Steps

(a) Solve 8x2+x=25x18^{-x^2 + x} = 2^{5x-1}.
First, rewrite 8 as 232^3:
(23)x2+x=25x1(2^3)^{-x^2 + x} = 2^{5x-1}.
Then, using the property (ab)c=abc(a^b)^c = a^{bc}:
23(x2+x)=25x12^{3(-x^2 + x)} = 2^{5x-1}.
Since the bases are equal, we can equate the exponents:
3(x2+x)=5x13(-x^2 + x) = 5x - 1
3x2+3x=5x1-3x^2 + 3x = 5x - 1
3x2+2x1=03x^2 + 2x - 1 = 0
We can factor this quadratic equation as:
(3x1)(x+1)=0(3x - 1)(x + 1) = 0
Therefore, 3x1=03x - 1 = 0 or x+1=0x + 1 = 0.
x=13x = \frac{1}{3} or x=1x = -1.
(b) Solve loga(2p+1)+loga(3p10)=loga(11p)log_a(2p+1) + log_a(3p-10) = log_a(11p) for p>0p>0.
Using the logarithm property loga(b)+loga(c)=loga(bc)log_a(b) + log_a(c) = log_a(bc):
loga((2p+1)(3p10))=loga(11p)log_a((2p+1)(3p-10)) = log_a(11p)
Since the logarithms have the same base, we can equate the arguments:
(2p+1)(3p10)=11p(2p+1)(3p-10) = 11p
6p220p+3p10=11p6p^2 - 20p + 3p - 10 = 11p
6p217p10=11p6p^2 - 17p - 10 = 11p
6p228p10=06p^2 - 28p - 10 = 0
Divide the equation by 2:
3p214p5=03p^2 - 14p - 5 = 0
We can factor this quadratic equation as:
(3p+1)(p5)=0(3p + 1)(p - 5) = 0
Therefore, 3p+1=03p + 1 = 0 or p5=0p - 5 = 0.
p=13p = -\frac{1}{3} or p=5p = 5.
Since p>0p>0, we discard the solution p=13p = -\frac{1}{3}. Also we have the condition that 3p10>03p-10>0 so p>103p > \frac{10}{3}. Since 5>1035 > \frac{10}{3}, p=5p=5 is a valid solution.
(c) Solve log2(x)3+log2(x+3)=0log_2(x) - 3 + log_2(x+3) = 0.
Using the logarithm property loga(b)+loga(c)=loga(bc)log_a(b) + log_a(c) = log_a(bc):
log2(x(x+3))3=0log_2(x(x+3)) - 3 = 0
log2(x(x+3))=3log_2(x(x+3)) = 3
Using the property loga(b)=c    ac=blog_a(b) = c \iff a^c = b:
x(x+3)=23x(x+3) = 2^3
x2+3x=8x^2 + 3x = 8
x2+3x8=0x^2 + 3x - 8 = 0
Using the quadratic formula x=b±b24ac2ax = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a}:
x=3±324(1)(8)2(1)x = \frac{-3 \pm \sqrt{3^2 - 4(1)(-8)}}{2(1)}
x=3±9+322x = \frac{-3 \pm \sqrt{9 + 32}}{2}
x=3±412x = \frac{-3 \pm \sqrt{41}}{2}
Since we must have x>0x>0, we discard the negative root. Thus
x=3+412x = \frac{-3 + \sqrt{41}}{2}

3. Final Answer

(a) x=13,1x = \frac{1}{3}, -1
(b) p=5p = 5
(c) x=3+412x = \frac{-3 + \sqrt{41}}{2}