Question

The equation x² – 1x – 90 = 0 has solutions {a, b}. What is a + b?

Answer 1

Good evening ,

______

Answer:

a+b=1

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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.

:)

Answer 2

a+b=1

Explanation:

we know that

The formula to solve a quadratic equation of the form
`ax^(2) +bx+c=0` is equal to

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

in this problem we have

`x^(2) -x-90=0`

so

`a=1\\b=-1\\c=-90`

substitute in the formula

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

`x=\frac{1(+/-)√(361)} {2}`

`x=\frac{1(+/-)19} {2}`

`x=\frac{1(+)19} {2}=10`

`x=\frac{1(-)19} {2}=-9`

so

a=10, b=-9

a+b=10-9=1