Can you guys please help me? I understand everything but the last step.
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Answer:
It is because you have to get rid of the power of 2 from c. In order to get rid, you have to square root it on both sides :
c² = 74
√(c²) = √74
c^(1/2×2) = √74
c = √74
Using Indices formula, (a^m)^n = a^(mn)