# Math Help - exponential equation

1. ## exponential equation

I am practicing for my exams need help to see if i'm doing the right thing. Thank you

Determine the values of x in the following exponential equations:

(a)3x×27x + 81 = 729

(b)(23x)x + 32 = 1/256

5. Solve the following equations:

(e) y = 2x (f) 2x – y + 2 = 0
y = x2 + 1 4x + y – 5 = 0

(g) x – y = 0
5x – 3y = 10

2. Do you mean
${3 \cdot x}^{27 \cdot x} +81 = 729$???

3. Originally Posted by Michelle Belford
I am practicing for my exams need help to see if i'm doing the right thing. Thank you

Determine the values of x in the following exponential equations:

(a)3x×27x + 81 = 729

(b)(23x)x + 32 = 1/256
(a)3x×27x + 81 = 729

did you mean the exponential equation $3^x \times 27^x +81 = 729 \;\;?$

4. ## REPLY TO SHYMAN ?

YES U R CORRECT

5. $3^x \times 27^x +81 = 729$
$3^x \times 3^{3\cdot x} = 729 - 81$
$3^{x+3\cdot x} = 648$
${4\cdot x} \cdot ln(3) = ln(648)$
$x = \frac{ln(648)}{4 \cdot ln(3)}$