9514 1404 393
Answer:
"complete the square" to put in vertex form
Step-by-step explanation:
It may be helpful to consider the square of a binomial:
(x +a)² = x² +2ax +a²
The expression x² +x +1 is in the standard form of the expression on the right above. Comparing the coefficients of x, we see ...
2a = 1
a = 1/2
That means we can write ...
(x +1/2)² = x² +x +1/4
But we need x² +x +1, so we need to add 3/4 to the binomial square in order to make the expressions equal:
_____
Another way to consider this is ...
x² +bx +c
= x² +2(b/2)x +(b/2)² +c -(b/2)² . . . . . . rewrite bx, add and subtract (b/2)²*
= (x +b/2)² +(c -(b/2)²)
for b=1, c=1, this becomes ...
x² +x +1 = (x +1/2)² +(1 -(1/2)²)
= (x +1/2)² +3/4
_____
* This process, "rewrite bx, add and subtract (b/2)²," is called "completing the square"—especially when written as (x-h)² +k, a parabola with vertex (h, k).
Responder:
c. x menos 25 menos estilo en línea fracción 4 entre 19 fin estilo paréntesis izquierdo x menos 25 paréntesis derecho igual 3
Explicación paso a paso:
Dado lo siguiente:
Cantidad original de gasolina en el tanque de combustible = x
Gasolina consumida en el primer viaje = 25 litros
Gasolina restante después del primer viaje = (x - 25) litros
Gasolina consumida en el segundo viaje = 4/19 de lo que queda, es decir;
(4/19) * (x - 25)
Gasolina restante después del segundo viaje = 3 litros
Cantidad inicial - cantidad consumida en el primer viaje - 4/19 de la cantidad restante después del primer viaje = 3
La gasolina que queda después del segundo viaje se puede modelar mediante la ecuación:
x - 25 - 4/19 (x - 25) = 3
Answer:
10 SENIORS
Step-by-step explanation:
x=# of seniors
y=# of juniors
x+y=23, x=2y-7
- plug the value of x in the second equation into the first
- (2y-7)+y=23
- Remove parentheses
- 2y-7+y=23
- Combine like terms
- 3y-7=23
- Add 7 to BOTH sides
- 3y=30
- divide BOTH sides by 3
- 3y/3=30/3
- y=10
- There are 10 juniors in the class
- FINAL STEPS
- Plug y (which is 10) into the first equation
- x+y=23
- x+10=23
- subtract 10 from BOTH sides
- x=13
- Since X equals the number of seniors, there are 10 seniors in the class
Answer:
1:20 scale should be perfect
Step-by-step explanation:
