Quadratic equation/Algebra Questions – Set 34
Directions (Q. Nos. 1 to 5) In the following questions, two equations A and B are given. You have to solve both the equations and
Give answer
- If x>y
- If x<y
- If x=y
- If xy
- If xy
1) 2x2+5x+1=x^2+2x-1
2y2-8y+1=-1
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Sol:
2x2+5x+1=x^2+2x-1
x2+3x+2=0
x2+2x+x+2=0
x(x+2)+1(x+2)=0
(x+2)(x+1)=0
x=-2,-1
2y2-8y+1=-1
2y2-8y+2=0
y2-4y+1=0
(+4±√(16-4×1×1))/(2×1)=2±√12=2±√3
Ans : b. Hence, y>x
2) x2/2+x-1/2=1
3y2-10y+8=y^2+2y-10
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Sol:
x2/2+x-1/2=1
x^2+2x-1=2
x^2+2x-3=0
x+3x-x-3=0
x(x+3)-1(x+3)=0
(x+3)(x-1)=0
x=-3, 1
3y2-10y+8=y^2+2y-10
2y^2-12y+18=0
y^2-6y+9=0
(y-3)^2=0
y=3, 3
Ans: b. y>x
3) 4x2-20x+19=4x-1
2y2=26y-84
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Sol:
4x2-20x+19=4x-1
4x^2-24x+20=0
x^2-6x+5=0
x^2-5x-x+5=0
x(x-5)-1(x-5)=0
(x-5)(x-1)=0
x=5, 1
2y2=26y-84
y^2=13y-42
y^2-13y+42=0
y^2-7y-6y+42=0
y(y-7)-6(y-7)=0
(y-7)(y-6)=0
y=7,6
Ans: b. y>x
4) y2+y-1=4-2y-y2
x2/2-3/2 x=x-3
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Sol:
y2+y-1=4-2y-y2
2y2+3y-5=0
2y^2+5y-2y-5=0
y(2y+5)-1(2y+5)=0
(2y+5)(y-1)=0
y=-5/2, 1
x2/2-3/2 x=x-3
x^2-3x=2x-6
x^2-5x+6=0
x^2-3x-2x+2×3=0
x(x-3)-2(x-3)=0
(x-3)(x-2)=0
x=3, 2
Sol: a. x>y
5) 6x2+13x=12-x
1+2y2=2y+5y/6
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Sol:
6x2+13x=12-x
3x^2+7x-6=0
(x+3)(3x-2)=0
x= -3, 2/3
1+2y2=2y+5y/6
1+2y^2=17y/6 y
12y^2-17y+6=0
12y^2-8y-9y+6=0
4y(3y-2)-3(3y-2)=0
(3y-2)(4y-3)=0
y=2/3,3/4
Ans: e. x≤y
Directions (Q. Nos. 6 to 10) In the following questions, two equations A and B are given. You have to solve both the equations and
Give answer
- If x>y
- If x≥y
- If x<y
- If x≤y
- If x=y or the relationship cannot be established
6) x2=169
y-√144=0
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Sol:
x2=169x=√169
x=±13
y-√144=0
y=√144
y=12
Ans: e. No relationship cannot be determined
7) 12x2+11x+12=10x2+22x
13y2-18y+3=9y2-10y
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Sol:
12x2+11x+12=10x2+22x
2x^2-11x+12=0
2x^2-8x-3x+12=0
(x-4)(2x-3)=0
x=4,3/2
13y2-18y+3=9y2-10y
4y^2-8y+3=0
4y^2-6y-2y+3=0
(2y-3)(2y-1)=0
y=3/2,1/2
Ans: b. x≥y
8) 18/x2 +6/x-12/x2 =8/x2
y3+9.68+5.64=16.95
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Sol:
18/x2 +6/x-12/x2 =8/x2
(18+16x-12)/x^2 =8/x^2
6x+6=8
x=2/6=0.33
y3+9.68+5.64=16.95
y^3=16.95-15.32
y^3=1.63
y=∛1.63
y=1.176
Ans: c. x < y
9) √1225x+√4900=0
811/4 y+3431/3 =0
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Sol:
√1225x+√4900=0
35x+70=0
x=-70/35=-2
811/4 y+3431/3 =0
3y+7=0
3y=-7
y=-7/3=-2.33
Ans: a. x>y
10) (25+113)/6=x3
4y3=-(589÷4)+5y3
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Sol:
(25+113)/6=x3
(32+1331)/6=x3
1363/6=x^3
x3=227.167
4y3=-(589÷4)+5y3
4y3= -589/4+5y3
589/4=y3
y3=147.25
y=5.280
Ans: a. x>y