Question

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

Answer 1

it can be factorised as

`(x - 10)(x + 9)`
so the solutions are
x= 10 and x = -9

so the sum of the solutions is 10 -9 which is 1

Answer 2

Value of a+b is:

1

Explanation:

For a equation

Ax²+Bx+C=0

if {a,b} are its solutions or equation has roots a and b

Then, sum of roots= -B/A and product of roots=C/A

i.e. a+b= -B/A and ab=C/A

Here, the equation is:

x² – x – 90 = 0

i.e. A=1,B= -1 and C= -90

then, a+b= -(-1)/1

i.e. a+b=1

Hence, value of a+b is:

1