What is the nature of roots of x- 9x = 20 ? a. nonreal
b. real, rational, and equal
c. real, rational, and unequal
d. real, irrational, and unequal

Option C

Step-by-step explanation:

To find the nature of the roots we use the Discriminant formula which is:

and given the equation and compare with the standard quadratic equation

Here our a is 1 , b is -9 and c is -20 so we plug a, b, c into the Discriminant formula

Since D > 0 (greater than zero) our roots are real and unequal for the rational and irrational part we got know the  the  Discriminant's square root value if it is in decimals the nature of the roots are irrational if the Discriminant's  value is a whole number then it is rational and so 161 has a square roots in points which is

So our answer is real , irrational and unequal which is Option C

the value of v.w= -12.

step-by-step explanation:

we are given three vector r,v and w as:

r = < 5, -5, -2> ; v = < 2, -8, -8> ; w = < -2, 6, -5>

we know that r,v and w could also be represented as:

r=5i-5j-2k

v=2i-8j-8k

and w= -2i+6j-5k

where i,j and k are the unit vectors of x,y and z-axis respectively.

also we know that it has the following property:

i.i=1 ; j.j=1; k.k=1

and i.=j.i=i.k=k.i=j.k=k.j=0

i.e. when we multiply two vectors or we find it's dot product we need to only multiply the components of x coordinates with each other; y with each other and z with each other.

hence, v.w= (2i-8j- -2i+6j-5k)

                  = 2×(-2)+(-8)×(6)+(-8)×(-5)

                  = -4-48+40

                  = -12

hence, v.w= -12

-4

step-by-step explanation: