Answer: B) Infinitely many solutions; both equations are equivalent
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Work Shown:
x+y = 4 ... start with the first equation
x + (-x+4) = 4 ... replace y with (-x+4)
x-x+4 = 4
0x+4 = 4
0+4 = 4
4 = 4 ... this is a true statement regardless of what x you pick
So there are infinitely many solutions. Each solution (x,y) is of the form (x,-x+4). All solutions fall on the line y = -x+4 which is equivalent to x+y = 4. Note how we add x to both sides.
Or you could start with x+y = 4 and subtract x from both sides to get y = -x+4. Either way, we're dealing with the same equation which is why they both graph out the same line.
The candle was 13 inches tall when it was first lit. It burns at a speed of 1.5 in. every hour. After burning for 6 hours it will be 4 inches tall.
Answer:
u = (-21)/20
Step-by-step explanation:
Solve for u:
u + 1/4 = (-4)/5
Put each term in u + 1/4 over the common denominator 4: u + 1/4 = (4 u)/4 + 1/4:
(4 u)/4 + 1/4 = -4/5
(4 u)/4 + 1/4 = (4 u + 1)/4:
1/4 (4 u + 1) = -4/5
Multiply both sides of (4 u + 1)/4 = (-4)/5 by 4:
(4 (4 u + 1))/4 = (-4)/5×4
4×(-4)/5 = (4 (-4))/5:
(4 (4 u + 1))/4 = (-4×4)/5
(4 (4 u + 1))/4 = 4/4×(4 u + 1) = 4 u + 1:
4 u + 1 = (-4×4)/5
4 (-4) = -16:
4 u + 1 = (-16)/5
Subtract 1 from both sides:
4 u + (1 - 1) = (-16)/5 - 1
1 - 1 = 0:
4 u = (-16)/5 - 1
Put (-16)/5 - 1 over the common denominator 5. (-16)/5 - 1 = (-16)/5 - 5/5:
4 u = (-16)/5 - 5/5
-16/5 - 5/5 = (-16 - 5)/5:
4 u = (-16 - 5)/5
-16 - 5 = -21:
4 u = (-21)/5
Divide both sides by 4:
u = ((-21)/4)/5
5×4 = 20:
Answer: u = (-21)/20
