solving math equations?

Question

2x - y = 0 and x - 2y = 3, then 6x - 6y = ?

a) 6 b) 12 c) 18 d) 21 e) 24


If x + y = 12 and x - y = (1/3), then x^2 - y^2 = ?

a) 36 b) 16 c) 8 d) 4 e) 2

explain pls

Answer 1

1.) y = 2x
x - 2(2x) = 3
x - 4x = 3
-3x = 3
x = -1
y = -2
so 6x - 6y = -6 + 12 = 6 (a)

2.) x = y + 1/3
y + 1/3 + y = 12
2y + 1/3 = 12
2y = 35/3
y = 35/6
x = 37/6

1369/36 - 1225/36 = 144/36 = 4 (d)

Answer 2

2x - y = 0 => 2x =y;
now substituting:

x - 2y = 3
x- 2(2x)=3 => x - 4x=3 => -3x = 3 => x=-1

Since 2x = y
2*(-1) = y = -2

6x - 6y = ?

6 * (-1) - 6 * (-2) = -6 +12 = 6

a) 6


If x + y = 12
x = 12-y

x - y = (1/3)

12-y-y = 1/3 => 12-2y = 1/3 => 36-6y=1 => -6y=-35 => y=35/6;

x=12 - 35/6 = 72/6 - 35/6 = 37/6

, then x^2 - y^2 = ?

(37/6)^2 - (35/6)^2 = 4

d) 4

Answer 3

(i) From 2x - y = 0 --> y = 2x. Put this in x - 2y = 3 yields

x - 4x = 3 --> x = - 1. Hence y = 2x = 2(- 1) = -2.

So 6x - 6y = 6(- 1) - 6(-2) = + 6.

(ii) We know x² - y² = ( x + y )(x - y ) = 12×(1/3) = 4. Hence (d) is the right answer!

Answer 4

Question 1
2x - y = 0
- 2x + 4y = - 6----ADD
3y = - 6
y = - 2

x + 4 = 3
x = - 1

6x - 6y = - 6 + 12 = 6
ANSWER a)

Question 2
ADD the two equations:-
2x = 12 1/3
2x = 37 / 3
x = 37 / 6
y = 12 - 37 / 6
y = 72 / 6 - 37 / 6
y = 35 / 6

x² - y² = (x - y) (x + y)
x² - y² = (2/6) (72/6) = (1/3) (12) = 4
ANSWER d)

Answer 5

1) 2x - y=0
2) x-2y =3
3(1 + 2) 3x -3y = 3
4( 2 x 3) 6x -6y = 6

answer is a

1) x + y = 12
2) x - y = 1/3
3 ( 1 x 2) 2x + 2y = 24
4(3-2) x + 3y = 71/3
5(4 - 1) 2y =72
y = 36
x= -24

Answer 6

Answer 1:
2x - y = 0
---> 2x = y ..... (1)

x - 2y = 3
x = 2y + 3 ..... (2)

Put (1) in (2),

x = 2(2x) + 3
x = 4x + 3
-3x = 3
x = -1

Put x = -1 in (1),

y = -2

x = -1, y = -2

6x - 6y = -6 + 12 = 6

Answer is a) 6

----------------- ----------------------- ---------------------- --------------

Answer 2:
x + y = 12 ..... (1)
x - y = 1/3 ..... (2)

x^2 - y^2 = (x + y)(x - y) = 12(1/3) = 4
Answer is d) 4

Answer 7

1.
2x-y=0 (1)
x-2y=3 (2)
(1)+(2) is
3x-3y=3 (3)
(3)*2is
6x-6y=6;
hence answer is a)6;
2.
x+y=12 (1)
x-y=1/3 (2)
(1)*(2) is
x^2-y^2=4;
hence the ans is
d).
in general to find ans 4 such question use the given equation to get to the point where u can get the answer

Answer 8

in case you divide the two facets of the equation by using -3, you finally end up with t = (-9)/(-3). This turns into t = 3 to income, you replace t with the end result (it is 3), and verify regardless of if the end results of the left area of the equation incredibly equals the the terrific option area of the equation. because -3x3 = -9, the answer is authentic.

Answer 9

1)
2x-y=0
x-2y=3
-----------------
3x-3y=3+0=3 then 6x-6y=6 then answer is "a"

2)
x+y=12
x-y=1/3
------------
(x=y)(x-y)=12*(1/3)=4
x^2-y^2=4 then answer is "d"

Answer 10

1. a) 6
Reason: Add two equations to get 3x-3y = 3. Then multiply both sides by two.

2. d) 4
Reason: Times two equations to get answer directly.