Which value must be added to the expression x2 – 3x to make it a perfect-square trinomial?

What number produces an irrational number when multiplied by -1.25

[10 points, algebra 2]according to my answer key the restrictions are -1 and 4. but why not positive 1?

The value of x in this system of equations is 1. 3x + y = 9 y = –4x + 10 substitute the value of y in the first equation: combine like terms: apply the subtraction property of equality: apply the division property of equality: 3x + (–4x + 10) = 9 –x + 10 = 9 –x = –1 x = 1 what is the value of y?