Brackets

• How to expand double brackets:

  (x+5)(x+3)

  Multiply them together:

  x²+5x+3x+15

  Simplify:

  x²+8x+15
• Solving equations with unknown on both sides:

  4(k+7)=12k-4

  Expand the brackets:

  4k+28=12k-4

  Decide which unknown has the smaller number in front of it. 4 is less than 12 so subtract 4k from both sides:

  4k+28 = 12k-4

  -4k. -4k

  28 =. 8k-4

  Add 4 to each side to cancel out 4:

  28. =. 8k-4

  +4. +4

  32=8k

  Divide both sides by 8:

  4=k

  The answer to the question is k is equal to 4