Answer:
x = 1, -7.5
Explanation:
2x² + 13x = 15
Divide the left side of the equation by 2
2(x² + 6.5x) = 15
Divide 6.5 by 2 and square the quotient
6.5/2 = 3.25
3.25² = 10.5625
Add 10.5625 to the left side
2(x² + 6.5x + 10.5625) = 15
Since you have a 2 outside the parentheses, you will be adding 10.5625•2 to the right side.
10.5625 • 2 = 21.125
2(x² + 6.5x + 10.5625) = 36.125
To factor (x² + 6.5x + 10.5625), add b/2 to x
b/2 = 6.5/2 = 3.25
2(x + 3.25)² = 36.125
Divide by 2
(x + 3.25)² = 18.0625
Square root.
(x + 3.25) = √18.0625
x + 3.25 = ±4.25
Subtract 3.25.
x = 4.25 - 3.25 = 1
x = -4.25 - 3.25 = -7.5
x = 1, -7.5
Method:
1) Find the atomic number in a periodic table: the number of electrons equal the atomic number
2) Use Aufbau rule
Element atomic number electron configuration
<span>
P 15 1s2 2s2 2p6 3s2 3p3
Ca 20 </span><span><span>1s2 2s2 2p6 3s2 3p6 4s2
</span>Si 14</span><span> 1s2 2s2 2p6 3s2 3p2
S 16</span><span><span> 1s2 2s2 2p6 3s2 3p4
</span>Ga 31. </span><span><span> 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p</span> </span>
Answer:
2.445 g
Explanation:
Step 1: Given and required data
- Energy in the form of heat required to boil the water (Q): 5525 J
- Latent heat of vaporization of water (∆H°vap): 2260 J/g
Step 2: Calculate the mass of water
We will use the following expression.
Q = ∆H°vap × m
m = Q / ∆H°vap
m = 5525 J / (2260 J/g)
m = 2.445 g