alleryFind the roots of x² + x − 20 = 0.
- x = −5 or 4
- x = −4 or 5
- x = −2 or 10
- x = −1 or 20
Show answer and solution
Correct answer: A. x = −5 or 4
The expression factors as (x+5)(x−4), giving roots −5 and 4.
ICSE Class 10 Quadratic Equations — practice questions — page 2
Explore 74 free Quadratic Equations questions in ICSE Class 10 Mathematics. Open each question or exercise to read its content, reference answers and available explanation.
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Showing questions 31–60 of 74.
Find the roots of x² + x − 20 = 0.Read the answer and worked solution →Which pair solves x² − 2x − 15 = 0?Read the answer and worked solution →Use the quadratic formula to solve 2x² − 7x + 3 = 0.Read the answer and worked solution →How many real roots does x² + 4x + 8 = 0 have?Read the answer and worked solution →For 3x² − 12x + 12 = 0, what is the nature of its roots?Read the answer and worked solution →What does a zero discriminant tell us about a quadratic equation?Read the answer and worked solution →A quadratic equation has discriminant −5. What can be concluded?Read the answer and worked solution →A rectangle has area 96 cm² and length 4 cm more than its breadth. Find the breadth.Read the answer and worked solution →A 100 km trip takes one hour less when speed rises from x to x+5 km/h. Find x.Read the answer and worked solution →One root of x² − 11x + 24 = 0 is 3. What is the other root?Read the answer and worked solution →For x² + kx + 16 = 0 to have equal roots, what is k²?Read the answer and worked solution →A rectangle’s length is 5 cm more than its breadth and area is 84 cm². Find its length.Read the answer and worked solution →After simplification, what degree has (x+2)²=x²+8?Read the answer and worked solution →Solve (x+1)³−x³=37.Read the answer and worked solution →Dividing x²=5x by x gives x=5. Which solution was lost?Read the answer and worked solution →Equating (x−1)(x+2) to 4 yields which roots?Read the answer and worked solution →The exact roots of 2x²−4x−1=0 areRead the answer and worked solution →Solve (3x−2)²=5 over the real numbers.Read the answer and worked solution →What solves x²/2−x/3−1/6=0?Read the answer and worked solution →The repeated root of x²−(2√3)x+3=0 isRead the answer and worked solution →Round the positive root of x²+x−1=0 to two decimal places.Read the answer and worked solution →For real k, x²−6x+k=0 has no real roots precisely whenRead the answer and worked solution →Multiplying ax²+bx+c=0 by 3 changes its discriminant D toRead the answer and worked solution →For (k−2)x²+4x+1=0, setting k=2 gives which solution?Read the answer and worked solution →For −2x²+3x+2=0, which quadratic-formula substitution is valid?Read the answer and worked solution →For x≠0, solve x+6/x=5.Read the answer and worked solution →With x≠2, which value solves x²/(x−2)=4/(x−2)?Read the answer and worked solution →Why does (x−2)(x−3) fail to factor x²−5x−6?Read the answer and worked solution →Two ages sum to 24 years. Four years ago their product was 60. Older person's age now?Read the answer and worked solution →Two constant-rate workers finish together in 6 days. Alone, one takes 5 days longer. Faster worker alone?Read the answer and worked solution →
Worked practice questions
Which pair solves x² − 2x − 15 = 0?
- −5 and 3
- −15 and 1
- −1 and 15
- −3 and 5
Show answer and solution
Correct answer: D. −3 and 5
Factoring gives (x−5)(x+3)=0, so the roots are 5 and −3.
Use the quadratic formula to solve 2x² − 7x + 3 = 0.
- x = 1/2 or 3
- x = 1 or 3
- x = −1/2 or 3
- x = 1/2 or −3
Show answer and solution
Correct answer: A. x = 1/2 or 3
The formula gives (7±5)/4, hence x=3 or x=1/2.
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