Write the factors of the quadratic equation: x^2 -4x-21=0

(x - 7)(x + 3) = 0

Step-by-step explanation:

To factorise the quadratic

Consider the factors of the constant term (- 21) which sum to give the coefficient of the x- term (- 4)

The factors are - 7 and + 3, since

- 7 × 3 = - 21 and - 7 + 3 = - 4, thus

(x - 7)(x + 3) = 0 ← in factored form

d. 24+-0.114

step-by-step explanation:

the question requires us to calculate the approximate 95% confidence interval for the mean number of ounces of ketchup per bottle in the sample given the following statistics;

sample mean = 24

standard deviation, σ = 0.4

sample size , n = 49

the confidence interval for a population mean is calculated using the formula;

sample mean ± z-score*(σ/sqrt(n))

the z-score associated with a 95% confidence interval, from the standard normal tables, is;

1.96

substituting these values into the formula;

24 ± 1.96*(0.4/7)

= 24 ± 0.112

from the alternatives given, choice d is closest to the above expression;