Question

Find the value of discriminant. 

i. x² + 7x – 1 = 0

ii. 2y² – 5y + 10 = 0 

iii. √2 x² + 4x + 2√2 = 0

Answer 1

i. x² +7 x – 1 = 0 

Comparing the above equation with ax² + bx + c = 0, we get 

a = 1, b = 7, c = -1 

∴ b² – 4ac = (7)² – 4 × 1 × (-1) 

= 49 + 4 

∴ b² – 4ac = 53

ii. 2y² – 5y + 10 = 0 

Comparing the above equation with ay² + by + c = 0, we get 

a = 2, b = -5, c = 10 

∴ b² – 4ac = (-5)² -4 × 2 × 10 

= 25 – 80 

∴ b² – 4ac = -55

iii. √2 x² + 4x + 2√2 = 0 

Comparing the above equation with ax + bx + c = 0, we get 

a = √2,b = 4, c = 2√2 

∴ b² – 4ac = (4)² – 4 × √2 × 2√2 

= 16 – 16 

∴ b² – 4ac =0