Answer:
w= 9
Step-by-step explanation:
Square both sides:
-4w +61= (w -4)²
Expand:
-4w +61= w² -2(w)(4) +4²
-4w +61= w² -8w +16
Simplify:
w² -8w +16 +4w -61= 0
w² -4w -45= 0
Factorize:
(w -9)(w +5)= 0
w -9= 0 or w +5= 0
w= 9 or w= -5 (reject)
Note:
-5 is rejected since we are only taking the positive value of the square root here. If the negative square root is taken into consideration, then w= -5 would give us -9 on both sides of the equation.
<u>Why </u><u>do </u><u>we </u><u>use </u><u>negative </u><u>square </u><u>root?</u>
When solving an equation such as x²= 4,
we have to consider than squaring any number removes the negative sign i.e., the result of a squared number is always positive.
In the case of x²= 4, x can be 2 or -2. Thus, whenever we introduce a square root, a '±' must be used.
However, back to our question, we did not introduce the square root so we should not consider the negative square root value.
Solution: The speed of old freight train is 0.5 miles per minute and the speed of new dart express train is 1.5 miles per minute.
Explanation:
Let the speed of old freight train is x miles per minute and the speed of new dart express train is y miles per minute.
It is given that the speed of the dart express train is three times faster than the freight train. So, it can be written as,
....(1)
The trains are moving towards the opposite directions, therefore the distance between them is increased at the speed of 
miles per minute.
The distance between both train in 15 minutes is represented by 
.
According to the given information the distance between trains is 30 miles in 15 minutes.
Use equation (1) and put 
Put this value in equation (1), to find the value of y.
Therefore, the The speed of old freight train is 0.5 miles per minute and the speed of new dart express train is 1.5 miles per minute.
Answer:
Step-by-step explanation:
y= -3/4x+3
Answer:
92776
Step-by-step explanation:
FIrst multiply:
9*10000= 90000
2*1000=2000
70*10= 700
Then add:
90000+2000+700+70(already given)+6(already given)= 92776
Hope this helps! :)
Answer:
3 * 10^6 if the answer is 3.64 * 10^6, you really ought to argue the meaning of estimate with your instructor.
Step-by-step explanation:
This is a very valuable question. Put your calculator away when you answer it. Using a calculator is sort of cheating.
1.3 * 10^3 roughly is roughly 1 * 10^3
2.8*10^3 hours is roughly 3 * 10^3
Forget the powers for now and just work with the 1 and 3
1*3 equals 3.
10^3 * 10^3 = 10^6 when the base of two numbers is the same (10 in this case) then the powers are added.
10^(3 + 3) = 10^6
So the answer is roughly 3*10^6
Now you can take out your calculator and get the answer.
1.3*10^3 * 2.8 * 10^3 = 3.64 * 10 ^ 6
Notice that the estimate (done in my head) is close enough to tell you what the answer should be. On a test, that's a very handy skill.
