Respuesta :

Answer:

a+b=1

Step-by-step explanation:

we know that

The formula to solve a quadratic equation of the form [tex]ax^{2} +bx+c=0[/tex] is equal to

[tex]x=\frac{-b(+/-)\sqrt{b^{2}-4ac}} {2a}[/tex]

in this problem we have

[tex]x^{2} -x-90=0[/tex]  

so

[tex]a=1\\b=-1\\c=-90[/tex]

substitute in the formula

[tex]x=\frac{1(+/-)\sqrt{-1^{2}-4(1)(-90)}} {2(1)}[/tex]

[tex]x=\frac{1(+/-)\sqrt{361}} {2}[/tex]

[tex]x=\frac{1(+/-)19} {2}[/tex]

[tex]x=\frac{1(+)19} {2}=10[/tex]

[tex]x=\frac{1(-)19} {2}=-9[/tex]

so

a=10, b=-9

a+b=10-9=1

Good evening ,

______

Answer:

a+b=1

___________________

Step-by-step explanation:

For such equation which has the form : mx² + nx + p = 0

There is a rule in this course that tells as: a + b = -(n)/m

We have m=1 and n= (-1) then a+b= -(-1)/1 = 1/1 = 1.

:)