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Which expression is equal to 2√28 + 2√63? A: 13√7 B: 4√7 C: 10√7 D: 12√7

1 Answer

3 votes

Answer:

C

Explanation:

Using the rule of radicals


√(a) ×
√(b)
√(ab)

Simplifying the radicals


√(28)

=
√(4(7))

=
√(4) ×
√(7) = 2
√(7)

and


√(63)

=
√(9(7))

=
√(9) ×
√(7) = 3
√(7)

Hence

2
√(28) + 2
√(63)

= 2(2
√(7) ) + 2(3
√(7) )

= 4
√(7) + 6
√(7)

= 10
√(7) → C

User Eabraham
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