Question

Solve the equation2.2^2x-7×2^x-4=0.
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Answer 1

2

Explanation:

• 2×2^2x - 7×2^x - 4=0
• 2×(2^x)^2 - 7×2^x - 4 = 0

Substitute 2^x = y, where y>0

Then we get quadratic equation:

• 2y^2 - 7y - 4 = 0

Solving this, we get y = 4 as positive root, so;

• y = 4
• 2^x = 4
• 2^x = 2^2
• x = 2

Answer is 2

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