Question

Evaluate after rationalising the denominator of 25 / √40 - √80,it being given that √5 = 2.236 and √10 = 3.162

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Answer 1

Step-by-step explanation:

25/√40-√80

=25/2√10-4√5

=25/2(√10-2√5)

=25(√10+2√5)/2(√10-2√5)(√10+2√5)

=25(√10+2√5)/2(10-20)

=-25(√10+2√5)/20

=-5(√10+2√5)/4

=-5(3.162+2×2.236)/4

=-5(3.162+4.472)/4

=-5×7.634/4

=-5×1.9085

=-9.5425