Question:
Tick (✓) the correct answer
If (23x − 1 + 10) ÷ 7 = 6, then x is equal to
(a) −2
(b) 0
(c) 1
(d) 2
Solution:
(d) 2
$\left(2^{3 x-1}+10\right) \div 7=6$
$\Rightarrow \frac{\left(2^{3 x-1}+10\right)}{7}=\frac{6}{1}$
$\left(2^{3 x-1}+10\right) \times 1=6 \times 7=42$
$\Rightarrow 2^{3 x-1}=42-10$
$\Rightarrow 2^{3 x-1}=32$
$\Rightarrow 2^{3 x-1}=2^{5}$
$\Rightarrow 3 x-1=5$
$\Rightarrow 3 x=6$
Therefore, $x=2$
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