# quick maths q

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#1
1.5x^.5 - 48x^-2 = 0

I know x is 3

but how do i find this out? taking logs? but how do i do that

thanks!
0
15 years ago
#2
(Original post by LondonBoy)
1.5x^.5 - 48x^-2 = 0

I know x is 3

but how do i find this out? taking logs? but how do i do that

thanks!
Multiply by x^2:

1.5x^2.5 - 48 = 0
1.5x^2.5 = 48
x^2.5 = 48/1.5
x = (48/1.5)^1/(2.5)
0
15 years ago
#3
(Original post by LondonBoy)
1.5x^.5 - 48x^-2 = 0

I know x is 3

Surely x is 4 ?

1.5 √ x = 3 = 48 ÷ 4²

Aitch
0
15 years ago
#4
(Original post by LondonBoy)
1.5x^.5 - 48x^-2 = 0

I know x is 3

but how do i find this out? taking logs? but how do i do that

thanks!

Just going to test my symbol paster:

1.5 √x = 48 ÷ x²
√x.x² = x^(5/2) = 32
x^5 = 1024
x = 4

I need to find a therefore. [ => looks a bit scratchy. ]

Gaz031's solution is more economical.

Aitch
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