Muft Shiksha
Update

Muft Shiksha™ एक 100% Free Education Portal है 🇮🇳, जिसका उद्देश्य Class 9–12 के हर विद्यार्थी तक High-Quality Education को पूरी तरह मुफ्त पहुँचाना है। 🇮🇳 हम मानते हैं कि अच्छी शिक्षा किसी student की आर्थिक स्थिति पर निर्भर नहीं होनी चाहिए। 🇮🇳 हर विद्यार्थी को वही Quality Study Material, MCQs, Quizzes, Exam Preparation, Concept-Based Learning और Bilingual Support मिलना चाहिए, जो आमतौर पर महंगी Coaching या Premium Platforms में मिलता है। Muft Shiksha™ 🇮🇳 इसी सोच के साथ बनाया गया है

Subjects
Class 9MathematicsExploring Algebraic IdentitiesQuadratic expressionsHard
0 reads0 ratings0 helpful

Which (k) makes (x^2+kx+81) a perfect square and (k) is negative?

Answer and explanation

Correct answer: (-18)

(81=9^2), so the negative middle term is (-2\cdot x\cdot9=-18x). In exams do not forget the given sign.

Related tags

Quadratic ExpressionsPerfect SquareUnknown CoefficientExploring Algebraic IdentitiesMathematicsClass 9 Mcq
सुधार सुझाएँ / Earn

Was this question useful?

No ratings yetWrite a review / Rate this question

Student Reviews

No published reviews yet.

KEEP PRACTISING

10 more MCQs
  1. 1Which expression can be factorised using the difference-of-cubes identity?
  2. 2What will be the factorised form of (r^2-2rs+s^2)?
  3. 3Which expression can be factorised directly using the identity for the difference of two squares?
  4. 4Which expression can be factorised directly using the difference-of-squares identity \(a^2-b^2=(a-b)(a+b)\)?
  5. 5Which expression is a quadratic expression?
  6. 6Based on the powers of the variable \(x\) in the polynomial \(5x^2-3x+7\), what is the degree of this expression?
  7. 7If a, b and c are constants, which condition is necessary for \(ax^2+bx+c\) to be a quadratic expression in x?
  8. 8If a quadratic expression has the general form \(ax^2+bx+c\), which condition on \(a\) is necessary for it to be quadratic?
  9. 9Which of the following expressions represents the square of the difference of two terms?
  10. 10Which of the following quadratic expressions can be factorised using the identity for the difference of two squares?
Found an issue? Help improve this questionMy reports and replies

Add Muft Shiksha to your Home Screen

In Safari, tap Share, then Add to Home Screen.