I don't think you can find x in this case. Cosine can only go as low as -1 and as high as 1. Since 2.3 is more than 1, the answer does not exist
You start off by multiplying the second bracket by -1 to get rid of the bracket.
So,
(2x3 + x2 - 4x) - 9x3 + 3x2 =
2x3 +x2 - 4x - 9x3 + 3x2 =
(2x3 - 9x3) + (x2 + 3x2) - 4x =
-7x3 + 4x2 - 4x
Answer:
12/7 hours
Step-by-step explanation:
First find the rate for hour for the two. For Lianne she can do 1/3 of the job per hour. For Julie she can do 1/4 of the job per hour.
Adding them together, 1/3+1/4= 7/12.
This 7/12 means that working together they can finish 7/12 of a job in an hour. We can use the speed*time=distance formula here and see that
7/12 * time = 1 job done
time = 12/7 hours.
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