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xz_007 [3.2K]
3 years ago
8

If (x + y)^2 = 105 and x^2 + y^2 = 65, what is the value of xy?

Mathematics
1 answer:
lesya692 [45]3 years ago
8 0
\boxed { \boxed {(a + b)^2 = a^2 + 2ab + b^2}}

(x + y) ^2 = 105

x^2 + 2xy + y^2 = 105

x^2 + y^2  + 2xy = 105


\text{Given that } x^2 + y^2 = 65,

65 + 2xy = 105

2xy = 105 - 65

2xy = 40

xy = 20

\boxed { \boxed {\text{Answer: xy = 20}}}
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1) El largo de un rectángulo mide el triple que su ancho. Si el ancho mide 12 cm, el perímetro del rectángulo es: Selecciona la
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Answer:

1) c) 96 cm

2) c) 17,15 m

3) c) 294 m

4) d) 332 metros

Step-by-step explanation:

1)

La fórmula para el perímetro de un rectángulo = 2L + 2W

= 2 (largo + ancho)

L = longitud

W = ancho

Se nos dice en la pregunta que:

La longitud de un rectángulo es tres veces su ancho. Si el ancho es de 12 cm

Por lo tanto,

L = 3 W

L = 3 × 12

Largo = 36cm

Por lo tanto, el perímetro =

2 (largo + ancho) cm

= 2 (36 + 12) cm

= 2 (48) cm

= 96 cm

2)

La fórmula para el perímetro de un heptágono regular = 7a

Donde a = longitud de un lado

De la pregunta,

a = 2,45 m laterales

Por lo tanto, el perímetro de un Heptágono regular = 7 (2,45 m)

= 17,15 m

3)

La fórmula para el perímetro de un rectángulo = 2L + 2W

= 2 (largo + ancho)

L = longitud

W = ancho

Se nos dice en la pregunta que:

Si un campo de fútbol tiene 98 m de largo y su ancho es igual a la mitad de esta medida,

Por lo tanto,

L = 98 m

W = 1/2 de longitud

Ancho = 1/2 (98)

= 49

Por lo tanto, el perímetro =

2 (largo + ancho) m

= 2 (98 + 49) m

= 2 (147) m

= 294 m

4)

El parque es de forma rectangular.

Longitud = 45 m

Ancho = 38.000 mm

Convertir mm en m

1 milímetro = 0,001 metro

38.000 milímetro =

38.000 × 0,001 metros

= 38 metros (38 m)

La distancia alrededor del parque = perímetro del parque

Perímetro = 2 (L + W)

= 2 (45 + 38)

= 2 (83)

= 166 m

Distancia alrededor del parque una vez = 166 m

Pero nos dijeron que dio la vuelta al parque 2 veces, por lo tanto, la distancia que recorrió = 166 m × 2

= 332m

4 0
3 years ago
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