The product of two rational numbers is always rational because (ac/bd) is the ratio of two integers, making it a rational number.
We need to prove that the product of two rational numbers is always rational. A rational number is a number that can be stated as the quotient or fraction of two integers : a numerator and a non-zero denominator.
Let us consider two rational numbers, a/b and c/d. The variables "a", "b", "c", and "d" all represent integers. The denominators "b" and "d" are non-zero. Let the product of these two rational numbers be represented by "P".
P = (a/b)×(c/d)
P = (a×c)/(b×d)
The numerator is again an integer. The denominator is also a non-zero integer. Hence, the product is a rational number.
learn more about of rational numbers here
brainly.com/question/29407966
#SPJ4
Answer:
There is enough evidence to say that the true average heat output of persons with the syndrmoe differs from the true average heat output of non-sufferers.
Step-by-step explanation:
We have to perform a hypothesis test on the difference between means.
The null and alternative hypothesis are:
![H_0: \mu_1-\mu_2=0\\\\H_a: \mu_1-\mu_2](https://tex.z-dn.net/?f=H_0%3A%20%5Cmu_1-%5Cmu_2%3D0%5C%5C%5C%5CH_a%3A%20%5Cmu_1-%5Cmu_2%3C0)
μ1: mean heat output for subjects with the syndrome.
μ2: mean heat output for non-sufferers.
We will use a significance level of 0.05.
The difference between sample means is:
![M_d=\bar x_1-\bar x_2=0.63-2.09=-1.46](https://tex.z-dn.net/?f=M_d%3D%5Cbar%20x_1-%5Cbar%20x_2%3D0.63-2.09%3D-1.46)
The standard error is
![s_{M_d}=\sqrt{\sigma_1^2/n_1+\sigma_2^2/n_2}=\sqrt{0.3^2/9+0.5^2/9}=\sqrt{ 0.038 } \\\\ s_{M_d}=0.194](https://tex.z-dn.net/?f=s_%7BM_d%7D%3D%5Csqrt%7B%5Csigma_1%5E2%2Fn_1%2B%5Csigma_2%5E2%2Fn_2%7D%3D%5Csqrt%7B0.3%5E2%2F9%2B0.5%5E2%2F9%7D%3D%5Csqrt%7B%200.038%20%7D%20%5C%5C%5C%5C%20s_%7BM_d%7D%3D0.194)
The t-statistic is
![t=\dfrac{M_d}{s_{M_d}}=\dfrac{-1.46}{0.194}=-7.52](https://tex.z-dn.net/?f=t%3D%5Cdfrac%7BM_d%7D%7Bs_%7BM_d%7D%7D%3D%5Cdfrac%7B-1.46%7D%7B0.194%7D%3D-7.52)
The degrees of freedom are
![df=n_1+n_2-2=9+9-2=16](https://tex.z-dn.net/?f=df%3Dn_1%2Bn_2-2%3D9%2B9-2%3D16)
The critical value for a left tailed test at a significance level of 0.05 and 16 degrees of freedom is t=-1.746.
The t-statistic is below the critical value, so it lies in the rejection region.
The null hypothesis is rejected.
There is enough evidence to say that the true average heat output of persons with the syndrmoe differs from the true average heat output of non-sufferers.
Tan x=opposite/adjacent
cot x=adjacent/opposite
so you need to inverse the fraction
tan x=.78 as a fraction is 78/100
-> inversed= 100/78=1.28=cot x
so it is the second option
Answer:
-12
Step-by-step explanation:
-|-12| = (-1)*| -12 | = - 12.
Recall the meaning of the absolute value function: It always returns a zero or positive result. Here, | -12 | = +12. Now, if there's a negative sign in front
of | -12 |, the final answer is -12.