Basic Equations - Online Quiz

Answer : C

Explanation

The given equations are
9x+ 2y = 198...(i)
2x+y =54...(iii)
On multiplying (ii) by 2 and subtracting it from (i), we get: 5x= 90 ⇒x= 18
Putting x=18 in (ii), we get: 36+y = 54 ⇒y = 18
∴x = 18, y= 18

Q 2 - On solving 4/x+5y=7 and 3/x+4y =5 we, get:

Answer : C

Explanation

Given equations are 4/x+5 y= 7 ...(i)
3/x+4y = 5  ...(ii)
On multiplying (i) by 3, (ii) by 4 and subtracting, we get -y =1 ⇒y= -1
Putting y= -1 in (i), we get 4/x-5 = 7 ⇒4/x= 12 ⇒12x= 4 ⇒x= 1/3
∴x= 1/3, y= -1

Q 3 - If 3x+7y= 75 and 5x-5y= 25, then what is the estimation of x+y?

Answer : D

Explanation

Given 3x+7y = 75  ...(i)
5x-5 y= 25 ⇒x-y = 5...(ii)
Multiplying (ii) by 7 and adding to (i), we get:
10 x = 110   ⇒x = 11
Putting x = 11 in (ii), we get: y=(11-5) = 6
∴ x+y = (11+6) = 17

Q 4 - On solving p/x+q/y = m, q/x+p/y = n, we get:

A - x=(q²-p²)/(mp-nq) , y = (q²-p²)/(np-mq)

B - x=(p²-q²)/(mp-nq), y=(p²-q²)/(np-mq)

C - x=(p²-q²)/(mp-nq) , y= (q²-p²)/(np-mq)

D - x=(q²-p²)/(mp-nq), y = (p²-q²)/(np-mq)

Answer : B

Explanation

Given equations are p/x+q/y = m...(i),   q/x+ p/y = n ...(ii)
On multiplying (i) by q, (ii) by p and subtracting, we get:
q²/y- p²/y = mq-np
⇒y (mp-np) = (q²- p²)
⇒y = (q²-p²)/(mq- np)
= (p²- q²)/(np-mq)
On multiplying (i) by p, (ii) by q and subtracting, we get:
p²/x - q²/x = mp- nq
⇒ (p²- q²) = x (mp- nq)
⇒x = (p²- q²)/ (mp-nq)
∴ x= (p²-q²)/(mp-nq) , y = (p²-q²)/(np- mq)

Q 5 - The arrangement of 3x-y+1/3 = 2x+y+2/5 = 3x+2y+1/6 are given by:

Answer : C

Explanation

We have (3x-y+1)/3= (2x+y+2)/5
⇒5 (3x-y+1) =3(2x+y+2)
⇒15x-5y+5 = 6x+3y+6
⇒9x-8y -1 = 0 ⇒9x-8y = 1 ...(i)
And (2x+y+2)/5 = (3x+2y+1)/6
⇒ 6 (2x+y+2) = 5(3x+2y+1)
⇒12x+6y +12=   15x+10 y+5
⇒3x+ 4y= 7...(ii)
Multiplying (ii) by 2 and adding (i) to it, we get: 15x= 15 ⇒x= 1
Putting x =1 in .., (ii), we get 3*1+4y= 7 ⇒4y = 4 ⇒y = 1
∴ x= 1, y = 1

Q 6 - On the off chance that x+1/y= 5, 2x+ 3/y= 13, then (2x-3y) =?

Answer : C

Explanation

X+1/y = 5...(i),     2x+3/y =13 ...(ii)
On multiplying (i) by 3 and subtracting (ii) from it, we get: x=2
Putting x= 2 in (i), we get 1/y =3 ⇒3y= 1 ⇒y = 1/3
∴ (2x-3y) = (2*2-3*1/3) = (4-1) = 3

Q 7 - The arrangement of x/2+y/3 =4 and x+y = 10 are given by:

Answer : C

Explanation

Given equation are 3x+2y = 24 ...(i), x+y =10 ...(ii)
On multiplying (ii) by 2 and subtracting from (i), we get: x=4
Putting x= 4 in (ii), we get: y = (10-4) = 6

Q 8 - The arrangement of mathematical statements 2x+ℏy= 11 and 5x-7y = 5 have no arrangement when:

Answer : C

Explanation

For no solution , we have a₁/a₂ = b₁/b₂ ≠c₁/c₂
i.e. 2/5 = ℏ/-7 ≠11/5 ⇒ℏ= -14/5

Q 9 - The arrangement of comparisons x+2y = 3 and 2x+ 4y = 3 have:

A - Precisely two arrangement

B - no arrangement

C - limitlessly numerous arrangement

D - an one of a kind arrangement

Answer : B

Explanation

Here a₁/a₂= 1/2, b₁/b₂=2/4=1/2 and c₁/c₂=3/3=1.
∴ a₁/a₂=b₁/b₂≠c₁/c₂.
∴Give system has no solution.

Q 10 - In the event that 3x-5y = 5 and x/x+y = 5/7, then (x-y) =?

Answer : A

Explanation

3x -5y=5 ...(i), 7x=5x+5y⇒2x-5y=0 ...(ii)
On subtracting (ii) from (i), we get=5.
3*5-5y=5⇒5y=10⇒y=2.
∴(x-y) = (5-2) =3.

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