Question

Evaluate -1/2 x² + 3/4 x for x = 4.

Answer 1

• -5

Solution:

1.Substitute

• Substitute x = 4 into
  `\sf{ - (1)/(2) {x}^(2) + (3)/(4) * }`
• 
  `\sf{ - \frac{ {4}^(2) }{2} + 4 * (3)/(4) }`

2.Calculate

• 
  `\sf{ - (16)/(2) + 4 * (3)/(4) }`
• Cross out the common factor
• 
  `\sf{ - 8 + 4 * (3)/(4) }`
• Cross out common factor
• 
  `\sf{ - 8 + 3}`
• Calculate the sum or difference
• -5

Hope it helps