Do V.
asked • 01/20/21Bradford T. answered • 01/20/21
I think the problem is:
(√1/7 - √2)/(√14-√42)
If you multiply the number and denominator with the conjugate of the denominator:
(√1/7 - √2)/(√14-√42) • (√14 + √42)/(√14 + √42) = ((√(14/7) + √(42/7) -√28 - √84)/(14-42)
= (√2+√6-√28-√84)/(-28) = (2√7 + 2√21 - √2 -√6)/28 ≈ 0.37832
I believe this is supposed to be an exercise in using conjugates and (a-b)(a+b) = a2-b2 to simplify the expression first.
Raymond B. answered • 01/20/21
sqr(1/7) - sqr(2/14) - sqr42=
sqr(1/7) - sqr(1/7) - sqr42 =
-sqr42 = about -6.48, round off to one decimal = -6.5
UNLESS you left out parentheses and intended to
say sqr(1/7) - sqr(2)/(sqr14 - sqr42) =
multiply by the conjugate, sqr14+sqr42
sqr(1/7) - sqr2(sqr14+sqr42)/(14-42) =
1/sqr7 + (sqr2(sqr14+sqr42)(+28) =
1/sqr7 + 2(sqr7 + sqr21)/28 =
1/sqr7 +(sqr7)(1+sqr3)/14 =
use a common denominator
14/14sqr7 + (7)(1+sqr3)/14sqr7 =
(21 + 7 + 7sqr3)/14sqr7 =
(28+7(1.732)/5.29 = about 0.89
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