05 Complex Numbers and Quadratic Equations
Exercise 03
Question:
Find the roots of the quadratic equation 2x^2+5x+3=0 by the method of completing the square.
Answer:
Step 1: Rewrite the equation in the form of ax^2+bx+c=0, where a, b, and c are constants.
2x^2+5x+3=0
Step 2: Divide each term by a (in this case, a = 2).
x^2 + (5/2)x + (3/2) = 0
Step 3: Rewrite the equation in the form of (x + h)^2 + k = 0.
(x + (5/4))^2 + (3/4) = 0
Step 4: Find the value of h.
h = (5/4)
Step 5: Find the value of k.
k = (3/4)
Step 6: Find the two roots of the equation.
x = -(5/4) ± √(-(3/4))
x = -(5/4) ± √(3/4)
Question:
x^2+x−2
Answer:
Step 1: Factor the expression.
(x - 2)(x + 1)
Step 2: Set each factor equal to zero.
x - 2 = 0 x + 1 = 0
Step 3: Solve each equation.
x = 2 x = -1
Question:
Solve : √2x^2+x+√2=0
Answer:
Step 1: Square both sides to get rid of the square root. 2x^2 + x + 2 = 0
Step 2: Rewrite the equation in standard form. 2x^2 + x - 2 = 0
Step 3: Factor the equation. (2x + 1)(x - 2) = 0
Step 4: Set each factor equal to zero and solve for x. 2x + 1 = 0 x = -1/2
x - 2 = 0 x = 2
The solutions are x = -1/2 and x = 2.
Question:
Solve : x^2+x+1/√2=0
Answer:
Step 1: Multiply both sides of the equation by √2
x^2 + x + 1 = 0 * √2
Step 2: Simplify the left side of the equation
2x^2 + 2x + 2 = 0
Step 3: Factor the left side of the equation
2(x^2 + x + 1) = 0
Step 4: Set each factor equal to 0 and solve for x
2 = 0 OR x^2 + x + 1 = 0
Step 5: Since 2 does not equal 0, solve for x in the second equation
x^2 + x + 1 = 0
x = [-1 ± √(-1^2 - 4(1)(1))] / 2
x = [-1 ± √(-1 - 4)] / 2
x = [-1 ± √(-5)] / 2
x = [-1 ± √5] / 2
x = [-1 ± 2.236] / 2
x = -1.618 or -0.382
Question:
Solve : x2+x/√2+1=0
Answer:
Step 1: Subtract 1 from both sides of the equation to get x2 + x/√2 = -1.
Step 2: Square both sides of the equation to get x2 + 2x + 1/2 = -1.
Step 3: Subtract 1/2 from both sides of the equation to get x2 + 2x = -3/2.
Step 4: Divide both sides of the equation by 2 to get x2 + x = -3/4.
Step 5: Subtract x from both sides of the equation to get x2 = -3/4 - x.
Step 6: Rewrite the equation in standard form to get x2 + x + (3/4) = 0.
Step 7: Factor the equation to get (x + (3/8))(x + (3/8)) = 0.
Step 8: Set each factor equal to 0 and solve for x to get x = -3/8.
Question:
For the quadratic equation x^2−2x+1=0, the value of x+1/x is : A −1 B 1 C 2 D −2
Answer:
Step 1: Rearrange the equation to get x^2 - 2x + 1 = 0
Step 2: Factor the equation to get (x - 1)(x - 1) = 0
Step 3: Set each factor equal to 0 and solve for x: x - 1 = 0 –> x = 1
Step 4: Substitute x = 1 into x + 1/x to get 1 + 1/1 = 2
Answer: C 2
Question:
Solve the equation x^2+3x+5=0 for x.
Answer:
-
First, subtract 5 from both sides of the equation to isolate the x terms: x^2+3x=-5.
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Next, factor the left side of the equation: x(x+3)= -5.
-
Divide both sides of the equation by (x+3) to isolate the x term: x=-5/(x+3).
-
To solve for x, set the denominator to 0 and solve for x: 0=x+3, x=-3.
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Therefore, the solutions to the equation x^2+3x+5=0 are x=-3 and x=-5/(x+3).
Question:
Solve : √3x^2−√2x+3√3=0
Answer:
Step 1: Square both sides of the equation: 3x^2 - 2x√3 + 9 = 0
Step 2: Rewrite the equation as a quadratic equation: 3x^2 - 2x√3 + 9 = 0 3x^2 - 2x√3 + 9 - 9 = 0 - 9 3x^2 - 2x√3 = -9
Step 3: Factor the equation: 3x^2 - 2x√3 = -9 3x(x - √3) = -9
Step 4: Divide both sides of the equation by 3: 3x(x - √3) = -9 (x - √3) = -3
Step 5: Solve for x: (x - √3) = -3 x - √3 = -3 x = -3 + √3
The solution to the equation is x = -3 + √3.
Question:
Solve following equation : x^2+3=0 A ±3 B ±3 C ±i3 D ±3i
Answer:
Answer: C ±i3
Question:
If α and β are the roots of the quadratic equation x^2−3x−2=0 then α/β+β/α A 3/2 B −3/2 C 13/2 D −13/2
Answer:
Step 1: Given equation is x^2−3x−2=0
Step 2: By using the quadratic formula, the roots of the equation can be determined.
α=(3+√17)/2
β=(3-√17)/2
Step 3: α/β+β/α= (3+√17)/2 / (3-√17)/2 + (3-√17)/2 / (3+√17)/2
Step 4: Simplifying, α/β+β/α= (3+√17)/(3-√17)+ (3-√17)/(3+√17)
Step 5: α/β+β/α= (3+√17 + 3-√17)/(3-√17)(3+√17)
Step 6: α/β+β/α= 6/(17-17)
Step 7: α/β+β/α= 6/0
Step 8: Since the denominator is 0, the answer is undefined.
JEE NCERT Solutions (Mathematics)
01 Sets
02 Relations and Functions
03 Trigonometric Functions
04 Principle of Mathematical Induction
05 Complex Numbers and Quadratic Equations
06 Linear Inequalities
07 Permutations and Combinations
08 Binomial Theorem
09 Sequences and Series
10 Straight Lines Exercise
10 Straight Lines Miscellaneous
11 Conic Sections
12 Introduction to Three Dimensional Geometry
13 Limits and Derivatives
14 Mathematical Reasoning
15 Statistics
16 Probability