If A = (1, 2, 3) and B = (x, y, z) such that A · B = 14, find the value of x + y

Practice Questions

Q1
If A = (1, 2, 3) and B = (x, y, z) such that A · B = 14, find the value of x + y + z.
  1. 5
  2. 6
  3. 7
  4. 8

Questions & Step-by-Step Solutions

If A = (1, 2, 3) and B = (x, y, z) such that A · B = 14, find the value of x + y + z.
  • Step 1: Understand that A = (1, 2, 3) and B = (x, y, z).
  • Step 2: The dot product A · B is calculated as 1*x + 2*y + 3*z.
  • Step 3: We know that A · B = 14, so we can write the equation: 1*x + 2*y + 3*z = 14.
  • Step 4: To find values for x, y, and z, we can make an assumption. Let's assume x = 2.
  • Step 5: Substitute x = 2 into the equation: 1*2 + 2*y + 3*z = 14.
  • Step 6: Simplify the equation: 2 + 2*y + 3*z = 14.
  • Step 7: Subtract 2 from both sides: 2*y + 3*z = 12.
  • Step 8: Now, we can assume another value for y. Let's assume y = 4.
  • Step 9: Substitute y = 4 into the equation: 2*4 + 3*z = 12.
  • Step 10: Simplify the equation: 8 + 3*z = 12.
  • Step 11: Subtract 8 from both sides: 3*z = 4.
  • Step 12: Divide both sides by 3 to find z: z = 4/3.
  • Step 13: Now we have x = 2, y = 4, and z = 4/3.
  • Step 14: Calculate x + y + z: 2 + 4 + 4/3.
  • Step 15: Convert 2 and 4 to fractions: 2 = 6/3 and 4 = 12/3.
  • Step 16: Add the fractions: 6/3 + 12/3 + 4/3 = 22/3.
  • Dot Product – Understanding the dot product of two vectors and how to set up the equation based on given values.
  • Variable Assignment – The importance of correctly assigning values to variables to satisfy the equation.
  • Linear Equations – Solving for multiple variables in a linear equation context.
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