BTEB Polytechnic Admission flashcards
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33 cards. Read the term and the definition here. The deck at the top of this page is optional.
- Quadratic formula
- For ax²+bx+c=0 with a≠0, the roots are x = (−b ± √(b²−4ac)) / 2a. The discriminant b²−4ac decides whether roots are real and distinct, equal, or complex.
- Sum of arithmetic progression
- The sum of the first n terms of an AP with first term a and common difference d is Sn = n/2 [2a + (n−1)d], equivalently n/2 (first term + last term).
- Area of a circle
- The area enclosed by a circle of radius r is πr², while its circumference is 2πr. Using π ≈ 3.1416, a circle of radius 7 has area about 154 square units.
- Trigonometric Pythagorean identity
- For any angle θ, sin²θ + cos²θ = 1. Dividing through by cos²θ gives 1 + tan²θ = sec²θ, and dividing by sin²θ gives 1 + cot²θ = cosec²θ.
- Combination formula
- The number of ways to choose r objects from n distinct objects without regard to order is nCr = n! / [r!(n−r)!]. Order matters in permutations but not in combinations.
- Newton's second law
- The net force on a body equals its mass times its acceleration, F = ma. The acceleration is in the direction of the net force, and weight is the special case W = mg.
- Third equation of motion
- For uniform acceleration a, initial velocity u and displacement s, the final velocity satisfies v² = u² + 2as. It is derived by eliminating time from the other two equations of motion.
- Ohm's law
- At constant temperature, the current through a conductor is directly proportional to the potential difference across it, so V = IR, where R is the resistance in ohms.
- Kinetic energy
- The kinetic energy of a body of mass m moving with speed v is ½mv². Doubling the speed quadruples the kinetic energy, since energy depends on the square of speed.
- Latent heat
- The heat needed to change the state of a substance without changing its temperature is Q = mL, where L is the specific latent heat of fusion or vaporisation.
- Snell's law
- When light passes between two media, sin i / sin r = n₂/n₁, where i and r are the angles to the normal. The refractive index also equals c/v.
- Mole concept
- One mole of any substance contains 6.022×10²³ particles and has a mass in grams numerically equal to its molar mass. It occupies about 22.4 L as an ideal gas at STP.
- Molarity
- Molarity is the number of moles of solute dissolved per litre of solution, M = n/V. During dilution the moles stay constant, so M₁V₁ = M₂V₂.
- pH scale
- pH is defined as −log[H⁺]. At 25 °C a solution with pH below 7 is acidic, pH exactly 7 is neutral, and pH above 7 is basic.
- Oxidation and reduction
- Oxidation is loss of electrons and an increase in oxidation number; reduction is gain of electrons and a decrease. The two always occur together in a redox reaction.
- Ideal gas equation
- For n moles of an ideal gas, PV = nRT, where R ≈ 8.314 J/(mol·K). Pressure times volume is proportional to absolute temperature at constant amount.
- Ionic versus covalent bond
- An ionic bond forms when one atom transfers electrons to another, typically between a metal and a non-metal. A covalent bond forms when non-metals share electron pairs.
- Present perfect tense
- The present perfect uses have or has plus the past participle, as in 'She has finished'. It links a past action to the present and cannot take a finished past time like yesterday.
- Passive voice formation
- The passive is formed with the correct tense of 'be' plus the past participle, and the active object becomes the subject: 'They built the bridge' becomes 'The bridge was built'.
- Third conditional
- The third conditional describes an unreal past situation: 'If + past perfect, would have + past participle', as in 'If I had studied, I would have passed'.
- Prepositions of time
- Use 'in' with months, years and seasons, 'on' with days and dates, and 'at' with exact clock times and fixed expressions such as at night.
- Subject-verb agreement
- A singular subject takes a singular verb and a plural subject a plural verb. With 'neither … nor' or 'either … or', the verb agrees with the nearer subject.
- স্বরবর্ণ ও ব্যঞ্জনবর্ণ
- বাংলা বর্ণমালায় স্বরবর্ণ ১১টি এবং ব্যঞ্জনবর্ণ ৩৯টি, মোট ৫০টি বর্ণ। স্বরবর্ণের সংক্ষিপ্ত রূপকে কার এবং ব্যঞ্জনবর্ণের যুক্ত রূপকে ফলা বলা হয়।
- সমাসের প্রকারভেদ
- বাংলা ভাষায় সমাস প্রধানত ছয় প্রকার: দ্বন্দ্ব, কর্মধারয়, তৎপুরুষ, বহুব্রীহি, দ্বিগু ও অব্যয়ীভাব। দুই বা তার বেশি পদের অর্থ সংক্ষেপ করে এক পদে প্রকাশ করাকে সমাস বলে।
- কারক কাকে বলে
- বাক্যে ক্রিয়ার সঙ্গে বিশেষ্যের যে সম্পর্ক থাকে তাকে কারক বলে। কর্তৃ, কর্ম, করণ, সম্প্রদান, অপাদান ও অধিকরণ - এই ছয় প্রকার কারক প্রচলিত।
- বাংলাদেশের স্বাধীনতা যুদ্ধ
- ১৯৭১ সালের ২৬ মার্চ স্বাধীনতা যুদ্ধ শুরু হয় এবং ১৬ ডিসেম্বর পাকিস্তান বাহিনীর আত্মসমর্পণের মাধ্যমে শেষ হয়। এ যুদ্ধ নয় মাস স্থায়ী হয়েছিল।
- জাতিসংঘের স্থায়ী সদস্য
- জাতিসংঘ নিরাপত্তা পরিষদের স্থায়ী সদস্য পাঁচটি: যুক্তরাষ্ট্র, যুক্তরাজ্য, ফ্রান্স, রাশিয়া ও চীন। এই সদস্যদের ভেটো দেওয়ার ক্ষমতা রয়েছে।
- বাংলাদেশের জাতীয় প্রতীক
- বাংলাদেশের জাতীয় ফুল শাপলা, জাতীয় পাখি দোয়েল, জাতীয় ফল কাঁঠাল, জাতীয় মাছ ইলিশ এবং জাতীয় পশু রয়েল বেঙ্গল টাইগার।
- Clock angle formula
- The angle between the hour and minute hands at H hours and M minutes is |30H − 5.5M| degrees. If the result exceeds 180, subtract it from 360 for the smaller angle.
- Ranking position formula
- For a person in a single row, total number of persons = (rank from left + rank from right) − 1, because the person is counted twice in the sum of the two ranks.
- Syllogism validity rule
- A conclusion follows from the premises only if it is true in every possible arrangement consistent with them. 'All A are B' never implies 'All B are A'.
- Binary and hexadecimal relation
- Binary uses base 2 and hexadecimal base 16. Each hexadecimal digit corresponds to exactly four binary bits, so conversion between these two bases is done group by group.
- Memory size units
- One byte equals 8 bits. One kilobyte is 1024 bytes, one megabyte is 1024 kilobytes, and one gigabyte is 1024 megabytes in binary-based measurement.