MCQ
If 9x+2 = 240 + 9x, then x =
- A0.5
- B0.2
- C0.4
- D0.1
✓
Answer
- 0.5
Solution:
We have to find the value of x
Given 9x+2 = 240 + 9x
9x × 92 = 240 + 9x
$9^2=\frac{240}{9^{\text{x}}}+\frac{9^{\text{x}}}{9^{\text{x}}}$
$81=\frac{240}{9^{\text{x}}}+1$
$81-1=\frac{240}{9^\text{x}}$
$80=\frac{240}{9^\text{x}}$
$9^\text{x}\times80=240$
$9^\text{x}=\frac{240}{80}$
$3^{2\text{x}}=3$
$3^{2\text{x}}=3^1$
By equating the exponents we get
$2\text{x}=1$
$\text{x}=\frac{1}{2}$
$\text{x}=0.5$
Hence the correct alternative is a.
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