the trinomial x2 bx c factors to (x m)(x n). if b is negative and c is positive, what must be true about m and n?
For c to be positive, and for b to be negative, m must be negative and n must be negative.
X^2 - bx + c = (x - m)(x - n).
c is the product of m and n. If both m and n are positive, c would be positive. However b is the sum of m and n, therefore to make b negative, both m and n must be negative to ensure that the product of m and n is positive
Answer:
Both m and n should be negative
Step-by-step explanation:
\((x - m)(x - n) = x^{2} -(m + n)x + mn\)
Comparing this with
\(x^{2} -bx+c\), we get,
b = m + n and c = mn
We have been given that c should be positive. So, we have two cases:
1. Both m and n should be positive and
2. Both m and n should be negative
Case 1: Both m and n are positive
If both m and n are positive, then so is mn = c.
But, note that m + n (= b) will also be positive. But, it is given that b should be negative. So, this case is not possible.
Case 2: Both m and n are negative
If both m and n are negative, then mn (= c) is positive.
Also, m + n (= b) is negative.
Hence, this is the correct case.