Bri goes to the movies and buys three items that together sum to $11.50. Two of the items she

Dado dos ángulos complementarios, uno mide (2x + 10) y el otro (x + 20),

rusak2 [61]

Answer:

El valor de x es igual a 20 o x = 20.

Step-by-step explanation:

Lo primero que se debe saber es que dos ángulos complementarios suman un ángulo recto o 90º.

Supongamos que el valor de un ángulo $\\ \alpha$ y un ángulo $\\ \beta$ valen:

$\\ \alpha = 2x + 10$ [1]

$\\ \beta = x + 20$ [2]

Como la suma de $\\ \alpha + \beta = 90$ [3]

Entonces

$\\ \alpha + \beta = (2x + 10) + (x + 20) = 90$

Sumamos los factores comunes entre si:

$\\ (2x + x) + (10 + 20) = 90$

Para la primera expresión debemos recordar que se suman sólo los coeficientes. Así:

$\\ (2 + 1)x + (10 + 20) = 90$

$\\ 3x + 30 = 90$

Para despejar la incógnita x, debemos tener en cuenta que una igualdad no se altera si se suma, se resta, se multiplica o divide un mismo valor a cada lado de ella. Por esta razón, para despejar 3x, lo primero que podemos hacer es sumar -30 a cada lado de la expresión (lo que es igual a restar 30 a cada lado de la misma). Así tenemos:

$\\ 3x + 30 - 30 = 90 - 30$

$\\ 3x + 0 = 90 - 30$

$\\ 3x = 60$

Ahora dividimos cada miembro de la igualdad entre 3 (o multiplicamos cada lado de la igualdad por $\\ \frac{1}{3}$ ):

$\\ \frac{3}{3}x = \frac{60}{3}$

Como sabemos que:

$\\ \frac{3}{3} = 1$

Entonces:

$\\ 1*x = \frac{60}{3}$

$\\ x = \frac{60}{3}$

$\\ x = 20$

De esta manera, el valor de x es igual a 20 o x = 20.

Lo anterior lo podemos comprobar considerando las ecuaciones [1], [2] y [3]. Así tenemos que:

$\\ \alpha = 2x + 10$ [1]

Sustituimos x por el valor de 20:

$\\ \alpha = 2*20 + 10 = 40 + 10 = 50$

$\\ \beta = x + 20$ [2]

Hacemos lo mismo para [2]:

$\\ \beta = 20 + 20$

$\\ \beta = 40$

De esta manera:

$\\ \alpha + \beta = 90$ [3]

$\\ 50 + 40 = 90$

4 0

3 years ago

The length of a rectangle is 5 more than the width. Find the length and width of a rectangle if the area of the rectangle is 36

harkovskaia [24]

Answer:

width = 4 in

length = 9 in

Step-by-step explanation:

To solve this problem, write an expression for the length and use the area of a rectangle formula.

The formula for area of a triangle is A = lw

"A" is the area.

"l" is the length.

"w" is the width.

"The length of a rectangle is 5 more than the width". It is represented in an expression:

l = w + 5 The width plus 5 is the length.

We also know the area is 36 in². Using information we know, replace variables in the formula for area of a rectangle.

Substitute l = w + 5 and A = 36

A = lw

36 = (w + 5)w Expand by multiplying w by the terms in the brackets.

36 = w² + 5w Since the equation is quadratic, make it equate to 0.

36 - 36 = w² + 5w - 36 Subtract 36 from both sides

0 = w² + 5w - 36 Factor this. Use group factoring, which is when you replace the middle term (5w) with two terms that add to make 5w, and multiply to get the last term (-36).

0 = w² + 9w - 4w - 36 9w times -4w is -36. They also add to get 5w.

0 = (w² + 9w) + (-4w - 36) Group the factors

0 = w(w + 9) + -4(w + 9) Take out the common factor in each group.

0 = w(w + 9) + -4(w + 9) Take out the new common factor binomial w+9

0 = (w + 9) (w - 4) Fully factored equation.

w + 9 = 0 w - 4 = 0 Set each binomial to equal 0.

w = -9 w = 4 Chose what makes sense to be the width.

The width cannot be a negative number, so the width is 4.

Since we know the width, we can find the length because the length is 5 more than the width.

l = w + 5

l = 4 + 5

l = 9 Length of the rectangle