Answer:
f(x) = - 4x² + 24x - 20
Step-by-step explanation:
Given
f(x) = - 4(x - 3)² + 16 ← expand the factor using FOIL
= - 4(x² - 6x + 9) + 16 ← distribute parenthesis by - 4
= - 4x² + 24x - 36 + 16 ← collect like terms
= - 4x² + 24x - 20
Answer:
Sister = 15 years old
Brother = 12 years old
Step-by-step explanation:
Right now, if the brother is B years old and the sister is S years old, B = (4/5)S because the ratio from brother to sister is 4:5, so if one unit is X, B = 4X and S = 5X
Three years ago, the brother was B-3 years old and the sister was S-3 years old. Keeping one unit as X, we have
B = 3X
S = 4X
B-3 = (3/4)(S-3)
Therefore, we have a system of equations
B = (4/5)S
B-3 = (3/4)(S-3)
Substitute (4/5)S for B into the second equation to only have one variable
(4/5)S - 3 = (3/4)(S-3)
(4/5)S - 3 = (3/4)S - 9/4
add 3 to both sides and subtract (3/4)S from both sides to isolate the variable and its coefficient
(1/20)S = 3/4
multiply both sides by 20 to isolate the S
S = 15
B = (4/5)S = 12
Answer:
3.45
Step-by-step explanation:
15 percent of 23
15 percent to decimal = 0.15
23 x 0.15 = 3.45
