Calculate the discriminant f(x)=x2-4x+7

Option 1,3,4,6 are correct

Explanation

Step-by-step explanation:

we have formula for discriminant that is D=b^{2} -4acD=b

2

−4ac

when D>0 the roots are real and unequal

when D= 0 roots are real and equal

and when D< 0 roots are imaginary or not real and unequal

In 1st equation: x^2+6x+8x

2

+6x+8

a=1,b=6,c=8 on substituting the values in the formula we will get

D=6^2-4(1)(8)=4 > 0D=6

2

−4(1)(8)=4>0 hence real and unequal roots.

In 2nd equation:x^2+4x+8x

2

+4x+8

a=1,b=4,c=8 on substituting values in formula

D=4^2-4(1)(8)=-16 < 0D=4

2

−4(1)(8)=−16<0 so roots are not real

In 3rd equation x^2-12x+3x

2

−12x+3

a=1,b=-12,c=3 on substituting values

D=D=(-12)^2-4(1)(3)=132 > 0D=(−12)

2

−4(1)(3)=132>0 roots are real and unequal

In 4th equation: x^2+4x-1x

2

+4x−1

a=1,b=4,c=-1 on substituting the values

D= 4^2-4(1)(-1)=20 > 0D=4

2

−4(1)(−1)=20>0 real roots

In 5th equation:5x^2+5x+45x

2

+5x+4

a=5,b=5,c=4 on substituting the values

D=5^2-4(5)(4)=-55 < 0D=5

2

−4(5)(4)=−55<0 roots are not real

In 6th Equation: x^2-2x-15x

2

−2x−15

a=1,b=-2,c=-15 on substituting the values

D=(-2)^2-4(1)(-15)=64 > 0D=(−2)

2

−4(1)(−15)=64>0 roots are real

ok

step-by-step explanation: