First, notice that:
![2\tan (\frac{x}{2})=2\cdot(\pm\sqrt[]{\frac{1-cosx}{1+\cos x})}](https://tex.z-dn.net/?f=2%5Ctan%20%28%5Cfrac%7Bx%7D%7B2%7D%29%3D2%5Ccdot%28%5Cpm%5Csqrt%5B%5D%7B%5Cfrac%7B1-cosx%7D%7B1%2B%5Ccos%20x%7D%29%7D)
And in the denominator we have:
then, we have on the original expression:
![\begin{gathered} \frac{2\tan(\frac{x}{2})}{1+\tan^2(\frac{x}{2})}=\frac{2\cdot\pm\sqrt[]{\frac{1-\cos x}{1+cosx}}}{\frac{2}{1+\cos x}}=\frac{2\cdot(\pm\sqrt[]{1-cosx})\cdot(1+\cos x)}{2\cdot(\sqrt[]{1+cosx})} \\ =(\sqrt[]{1-\cos x})\cdot(\sqrt[]{1+\cos x})=\sqrt[]{(1-\cos x)(1+\cos x)} \\ =\sqrt[]{1-\cos^2x}=\sqrt[]{\sin^2x}=\sin x \end{gathered}](https://tex.z-dn.net/?f=%5Cbegin%7Bgathered%7D%20%5Cfrac%7B2%5Ctan%28%5Cfrac%7Bx%7D%7B2%7D%29%7D%7B1%2B%5Ctan%5E2%28%5Cfrac%7Bx%7D%7B2%7D%29%7D%3D%5Cfrac%7B2%5Ccdot%5Cpm%5Csqrt%5B%5D%7B%5Cfrac%7B1-%5Ccos%20x%7D%7B1%2Bcosx%7D%7D%7D%7B%5Cfrac%7B2%7D%7B1%2B%5Ccos%20x%7D%7D%3D%5Cfrac%7B2%5Ccdot%28%5Cpm%5Csqrt%5B%5D%7B1-cosx%7D%29%5Ccdot%281%2B%5Ccos%20x%29%7D%7B2%5Ccdot%28%5Csqrt%5B%5D%7B1%2Bcosx%7D%29%7D%20%5C%5C%20%3D%28%5Csqrt%5B%5D%7B1-%5Ccos%20x%7D%29%5Ccdot%28%5Csqrt%5B%5D%7B1%2B%5Ccos%20x%7D%29%3D%5Csqrt%5B%5D%7B%281-%5Ccos%20x%29%281%2B%5Ccos%20x%29%7D%20%5C%5C%20%3D%5Csqrt%5B%5D%7B1-%5Ccos%5E2x%7D%3D%5Csqrt%5B%5D%7B%5Csin%5E2x%7D%3D%5Csin%20x%20%5Cend%7Bgathered%7D)
therefore, the identity equals to sinx
A rational number is an algebraic term expressed as a fraction. The fraction can also be in decimals but only if the decimal places are not repeating or not infinitely long. If they aren't, then these are called irrational numbers.
Let's try each of the choices:
A. The term 2/4 is a rational number. Now, when 0.3 or 3/10 is added to it, the sum would be 4/5 or 0.8. This is a rational number.
B. √7 is an irrational number because its exact value is 2.645751311.... Even if you add 0.3 to it, the answer would still be irrational
C. Obviously, this is an irrational number
D. The exact value of π is <span>3.14159...... If 0.3 is added to it, the answer would be 3.441592654. This is irrational.
Therefore, the answer is A.</span>
Answer:
see explanation
Step-by-step explanation:
(a)
Given
x² + 5x + 6
Consider the factors of the constant term ( + 6) which sum to give the coefficient of the x- term ( + 5)
The factors are 3 and 2, since
3 × 2 = 6 and 3 + 2 = 5, hence
x² + 5x + 6 = (x + 3)(x + 2) ← in factored form
(b)
To solve
x² + 5x + 6 = 0 ← use the factored form, that is
(x + 3)(x + 2) = 0
Equate each factor to zero and solve for x
x + 3 = 0 ⇒ x = - 3
x + 2 = 0 ⇒ x = - 2
Answer:
Step-by-step explanation:
-3y = 4x +9
y= -3/4x -3
13. (a-b)^2=a^2-2ab+b^2
B is the answer
14. B is the answer
( x+9)(x-3)= x^2+6x-27
15. B is the answer
(x+6)(x-5)=x^2+x-30
16. D is the answer
(x-6y)(x-4y)=x^2-10xy+24y^2
17. C is the answer
(2x+5)(3x-4)=6x^2+7x-20
18. B is the answer
(5x+7)(x-2)=5x^2-3x-14
