2000. Because if you add the 2 it will make 1200, 2+8 is 10 so you carry the 1, and 3+9 is 12 then you add the 1 you got from 10 and you have 13. then you add 1+1 and get 2 and add the 1 you got from 13 so there you have it.
Step-by-step explanation:
#1.
(a + 2b)²
<em>Using identity (x + y)² = x² + 2xy + y², we get:</em>
= (a)² + (2b)² + 2 × (a) × (2b)
= a² + 4b² + 4ab
= a² + 4ab + 4b² Ans.
#2.
(5x - 3y)²
<em>Using identity (a - b)² = a² - 2ab + b², we get:</em>
= (5x)² + (3y)² - 2 × (5x) × (3y)
= 25x² + 9y² - 30xy
= 25x² - 30xy + 9y² Ans.
#3.
(3a + 4)(3a - 4)(9a² + 16)
<em>Using identity (x + y)(x - y) = x² - y², we get:</em>
= [(3a)² - (4)²][9a² + 16]
= (9a² - 16)(9a² + 16)
= (9a²)² - (16)²
= 81a⁴ - 256 Ans.
So, f[x] = 1/4x^2 - 1/2Ln(x)
<span>thus f'[x] = 1/4*2x - 1/2*(1/x) = x/2 - 1/2x </span>
<span>thus f'[x]^2 = (x^2)/4 - 2*(x/2)*(1/2x) + 1/(4x^2) = (x^2)/4 - 1/2 + 1/(4x^2) </span>
<span>thus f'[x]^2 + 1 = (x^2)/4 + 1/2 + 1/(4x^2) = (x/2 + 1/2x)^2 </span>
<span>thus Sqrt[...] = (x/2 + 1/2x) </span>
(4x - y)/(2y + x) when x = 3 and y = 3 is
(4(3) - 3)/(2(3) + 3) = (12 - 3)/(6 + 3) = 9/9 = 1
