Answer:
paper clips = $1.85
index cards = $3.95
Step-by-step explanation:
Mark
12 paper clips = x
10 index cards = y
$61.70 total
Janice
15 paper clips = x
7 index cards = y
$55.40 total
12x + 10y = 61.70
15x + 7y = 55.40
*** you want to cancel out one of the letters
(12x + 10y = 61.70) * -7
(15x + 7y = 55.40) * 10
-84x -70y = -431.9
150x + 70y = 554.0
150x + 70y = 554.0
-84x -70y = -431.9
66x + 0 = 122.1
66x = 122.1
x = 122.1 ÷ 66
x = 1.85
plug it back in
15(1.85) + 7y = 55.40
27.75 + 7y = 55.40
7y = 55.40 - 27.75
7y = 27.65
y = 27.65 ÷ 7
y = 3.95
Answer:
14.99 hours
Step-by-step explanation:
The formula for half-life is given as,
R/R' = 2ᵃ/ᵇ...................... Equation 1
Where R= Original mass of sodium-24, R' = mass of Sodium-24 after disintegration, a = Total time taken for sodium-24 to disintegrate, b = half-life of sodiun-24.
Given: R = 1 kg, R' = 0.0156 kg, a = 90 hours
Substitute into equation 1 and solve for b
1/(0.0156) = 2⁹⁰/ᵇ
Taking the log of both side
log[1/(0.0156)] = log(2⁹⁰/ᵇ)
log[1/(0.0156)] = 90/b(log2)
90/b = log[1/(0.0156)]/log2
90/b = 6.0023
b = 90/6.0023
b = 14.99 hours
b = 14.99 hours.
Hence the half-life of Sodium-24 is 14.99 hours
Answer:
The first one
Step-by-step explanation:
Mark me brainliest please
Answer: The correct factors are
(x-1) and (x+2)
Step-by-step explanation:
Step one :
To factorize the equation
x²– x – 2=0
First we look for numbers that when multiplied will result to the constant term and when added will result to the second term (1x, - 2x)
Step two :
We replace the second term with these factors we have
x²–(x-2x)–2=0
x²–x+2x–2=0
Factoring the expression we have
x(x–1)+2(x–1)=0
Hence the factors will be
(x-1) and (x+2)
Given:
The figure of two quadrilaterals.
In 
In 
To find:
Whether the figures are congruent, similar or neither.
Solution:
Ratio of corresponding sides are:
Similarly,
And,
Clearly, 
.
All corresponding sides are not proportional.
Therefore, the figures are neither similar nor congruent. Hence, third option is correct.
