Powers and Roots Practice Test 5

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Question : 6 of 31

Marks: +1, -0

What is the square root of

(0.84)^3/{1-0.84}+[0.84+(0.84)^2+1]

?

6.25
7.5
3.5
2.5
15.1

Solution:

√{(0.84)^3/{1-0.84}+[0.84+(0.84)^2+1]}

=√{{(0.84)^3 +({1-0.84})[(1)^2 +(0.84)^2 +1×0.84]}/{1-0.84}}

[ By using:

a^3-b^3=(a-b)(a^2+b^2+ab)

]

=√{{(0.84)^3+(1)^3-(0.84)^3}/0.16}

=√{1/0.16}

=√{100/16}=10/4=2.5

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