How is mathematical thinking established? How can we have mathematical thinking? 修改翻译结果
2 answers:
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Therefore, the answer is the first choice.
Answer:
correct option is C) 2.8
Step-by-step explanation:
given data
string vibrates form = 8 loops
in water loop formed = 10 loops
solution
we consider mass of stone = m
string length = l
frequency of tuning = f
volume = v
density of stone =
case (1)
when 8 loop form with 2 adjacent node is
so here
..............1
and we know velocity is express as
velocity = frequency × wavelength .....................2
= f ×
here tension = mg
so
= f ×
..........................3
and
case (2)
when 8 loop form with 2 adjacent node is
..............4
when block is immersed
equilibrium eq will be
Tenion + force of buoyancy = mg
T + v × × g = mg
and
T = v × - v ×
× g
from equation 2
f × = f ×
.......................5
now we divide eq 5 by the eq 3
solve irt we get
so
relative density
relative density = 2.78 ≈ 2.8
so correct option is C) 2.8
answer
D 2
factor
factor the equation into (x + a) and (x + b) so that a + b = -2 and a * b = -8
the two numbers that meet these conditions are a = -4 and b = 2
find solutions
set both (x - 4) and (x + 2) equal to zero to find your solutions
x - 4 = 0
x = 4
x + 2 = 0
x = -2
add solutions
since the two solutions are x = 4 and x = -2, add them together to get your final answer
4 + (-2) = 2