Hello :
the nth term ( general term of an arithmetic sequence is :
An =A1+(n-1)d ....a common difference is : d , A1 : the first terme
A1 = 5 and : d = 1 - 5 = - 4 n = 21
A21 = 5 + (21 -1)(-4)
A21 = 5 - 80 = -75
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<span>∵ There is a proportional relationship between the mass and the volume of the places of metal.
Let volume = v and mass = m
So, the relation between volume and mass will take the form:
v = km
where k is constant and can be calculated as follow:
when m = </span><span>34.932 , and v = 4.1 ⇒⇒⇒ k = v/m = 0.117371
</span>when m = 47.712<span> , and v = 5.6 ⇒⇒⇒ k = v/m = </span>0.117371
when m = 61.344 , and v = 7.2 ⇒⇒⇒ k = v/m = <span>0.117371
when m = </span>99.684 , and v = 11.7 ⇒⇒⇒ k = v/m = <span>0.117371
∴ v = 0.117371 m
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For v =<span>15.3
∴ m = v/k = 15.3/0.117371 = 130.356 </span><span>gram
</span>The mass of a piece of this metal that has a volume of 15.3 cubic centimeters ≈ 130.4 gram (<span>round to the nearest tenth</span>)
I think you mean 8x^2 + 7 =0
a = 8 b = 0 c = 7
x= [-b +- square root (b^2 - 4*a*c)] / 2a
x = [0 +- square root (0 - 4*8*7)] / 2*8
x = +- square root (-224) / 16
x = +-
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14.9666295471 * i
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/ 16
x = +
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<span>
0.9354143467
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</span>
</span>
i
x = -
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<span>
0.9354143467
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</span>
i
