a. x^2 − 2x − 3 = 0 {nl} b. x^2 + 2x − 3 = 0 {nl} c. x^2 − 4x + 3 = 0 {nl} d. x^2 + 4x + 3 = 0
+140 x=1 and x=-3 so it is (x-1) and (x+3)
added together -1 and 3 equal 2 and when multiplied equal -3 so look for the equation with their product (-3) as the constant (no variable) and their sum (2) as the coeficient of the middle term
so the correct answer is b.
to check
(x-1)(x+3)
x^2 + 3x - x - 3
x^2 + 2x - 3
+129899 We have the form Ax^2 + BY + C = 0
In any quadratic......the sum of the solutions = -B/A
So ..... the sum of the solutions = -2 and note that A = 1 in every answer ....so....we can solve for "B" thusly :
-2 = -B/A
-2 = -B / 1
-2 = -B → B = 2
The only equation that has B = 2 is the second one
