Question

Pls tell me the answer for these questions

d04daf6ca97f44851c6619aece74a1b1.pdf

Answer 1

1. Expand the following:

  a)    (4x + 7y)²

      = (4x)² + 2(4x)(7y) + (7y)²

      = 16x² + 56xy + 49y²

  b)    (3x - 7y)²

      = (3x)² - 2(3x)(7y) + (7y)²

      = 9x² - 42xy + 49y²

   c)    (2x + 3y - 6z)²

      = [(2x + 3y) - 6z]²

      = (2x + 3y)² - 2(2x + 3y)(6z) + (6z)²

      = (2x)² + 2(2x)(3y) + (3y)² - 2(12xz + 18yz) + 36z²

      = 4x² + 12xy + 9y² - 24xz - 18yz + 36z²

   d)   (3x - $\frac{1}{3x}$)²

      = (3x)² - 2(3x)($\frac{1}{3x}$) + ($\frac{1}{3x}$)²

      = 9x² - $\frac{6x}{3x}$ + $\frac{1}{9x^{2} }$

      = 9x² - 2 + $\frac{1}{9x^{2} }$

   e)   (2x - $\frac{1}{2x}$)²

      = (2x)² - 2(2x)($\frac{1}{2x}$) + ($\frac{1}{2x}$)²

      = 4x² - $\frac{4x}{2x}$ + $\frac{1}{4x^{2} }$

      = 4x² - 2 + $\frac{1}{4x^{2} }$

I'm sorry that I don't know how to do (2) and (3).