If = 7 − 4√3, find the value of √a + 1 /√a .
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Step-by-step explanation:
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Step-by-step explanation:
a= 7-4√3
1/a = 1/(7-4√3)
on rationalising
1/a = {1×(7+4√3)}/{(7-4√3)(7+4√3)
1/a = (7+4√3)/49-48.
{using (a+b)(a-b) = a^2 -b^2 }
1/a = 7+4√3
now
a + 1/a = 7-4√3 + 7 + 4√3
a+ 1/a = 14
we can write (a) = (√a)^2
because of √a×√a= a
(√a)^2 + (1)^2/ (√a)^2 = 14
(√a)^2 + {1/(√a)}^2 = 14
add 2(√a)(1/√a) both sides
(√a)^2 +{1/(√a)}^2 + 2(√a)(1/√a) = 14 + 2(√a)(1/√a)
using (a)^2 + (b)^2 + 2 ab = (a+ b ) ^2
( √a + 1/√a)^2 = 14 + 2 { 2√a × 1/√a =2}
(√a +1/√a ) = √16
√a+1/√a = 4 or -4
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