Question

i need step wise to this question x^2-15x+90=0

Answer 1

My friend there is 3 methods to solve this problem which one you choose
1st middle turn bracket
2nd shridhar acharya
3rd method of completing the square

lets go with easy one i mean first one

x^2-15x+90=0
We can't solve this question with 1st method, if we will, we get decimal 7.23 something like this so i prefer 2nd method.
x=-b+-√(b^2-4ac)/2a
put the value we get
x=15+-√(225-4×1×90)/2×1
x=15+-√(225-360)/2
x= imaginary number, so we will do this with help of iota "i"
x=(15+-√-135)/2 ans

Answer 2

x^2-15+90=0
Discriminent D=b^2-4ac
                     D=(-15)^2-4(1)(90)
                      D=225-360
                       D=-135

                      x=( -b+-√D)/2a
                       x=(-(-15)+-√-135))/2.1    we know i^2=-1 so √I^2=i
                        x=(15+-√135 i)/2
                        x=15/2+-3√15/2