How to solve (x+7)(x-9)>0
1 answer:
Answer:
x < -7, x > 9.
Step-by-step explanation:
Solve for x.
x = -7, 9
From the values of x above, we have these 3 intervals to test.
Pick a test point for each interval.
For the interval x < −7:
Let's pick x=−8. Then, (-8 + 7) (-8 - 9) > 0.
After simplifying, we get 17>0, which is true
Keep this interval.
Let's pick x=0. Then, (0+7)(0-9) > 0.
After simplifying, we get −63 > 0, which is false.
Drop this interval.
For the interval x > 9:
Let's pick x=10. Then, (10+7)(10-9)>0.
After simplifying, we get 17 > 0, which is true
Keep this interval.
Therefor, the answer is x < -7, x > 9.
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Answer:
volume = 7 * 4 * 24 = 672 m 3
Step-by-step explanation:
a^2 = 25^2 - 7^2 = 576
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volume = 7 * 4 * 24 = 672 m 3
<h2>Answer : (2.67, 3.53)</h2><h2></h2>
Step to step explanation:
Confidence interval for mean, when population standard deviation is unknown:
, where = sample mean
n= sample size
s= sample standard deviation
= Critical t-value for n-1 degrees of freedom
We assume the family size is normal distributed.
Given, n= 31 , , s= 1.42 ,
Critical t value for and degree of 30 freedom
= 1.697 [By t-table]
The required confidence interval:
Hence, the 90% confidence interval for the estimate = (2.67, 3.53)