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AP · Class 8 · 🧮 Maths · Chapter 11

Direct and Inverse Proportions

అనులోమ అనుపాతంవిలోమ అనుపాతంఅనుపాతాల అనువర్తనాలుx/y స్థిరంxy స్థిరం

అనులోమ మరియు విలోమ అనుపాతాలు అనే అధ్యాయం రెండు పరిమాణాలు ఒకదానికొకటి ఎలా సంబంధం కలిగి ఉన్నాయో వివరిస్తుంది. ఒక పరిమాణం పెరిగినప్పుడు మరొకటి కూడా అదే నిష్పత్తిలో పెరిగితే అది అనులోమ అనుపాతం అవుతుంది. ఉదాహరణకు, ఎక్కువ వస్తువులు కొంటే ఎక్కువ ఖర్చు అవుతుంది. ఒక పరిమాణం పెరిగినప్పుడు మరొకటి తగ్గుతూ ఉంటే అది విలోమ అనుపాతం. ఉదాహరణకు, వేగం పెరిగితే ప్రయాణ సమయం తగ్గుతుంది. ఈ భావనలు రోజువారీ జీవితంలో అనేక సమస్యలను పరిష్కరించడానికి ఉపయోగపడతాయి, ఇది విద్యార్థులకు చాలా ముఖ్యమైనది.

Introduction to Proportions

Jab do quantities ek dusre par depend karti hain aur ek ke badalne se doosri bhi badalti hai, toh hum kehte hain ki woh proportion mein hain.

  • Example:
  • Agar aap zyada pen khareedte hain, toh total cost bhi zyada hogi. (Direct)
  • Agar aapki gaadi ki speed badhti hai, toh destination tak pahunchne mein kam time lagega. (Inverse)
  • Proportion ka concept real-life situations mein bahut useful hai.
ముఖ్యమైనది

Proportion ka matlab hai do ratios ki equality. Jab do quantities ek specific tarike se relate karti hain, toh unhe proportional kaha jata hai.

Direct Proportions

Jab do quantities is tarah se related hoti hain ki ek ke badhne par doosri bhi badhti hai, aur ek ke ghatne par doosri bhi ghat jaati hai, toh unhe direct proportion mein kaha jata hai.

  • Key Idea: Unka ratio hamesha constant rehta hai.
  • Agar \(x\) aur \(y\) direct proportion mein hain, toh \(\frac{x}{y} = k\) (jahan \(k\) ek constant hai).
  • Iska matlab hai, \(\frac{x_1}{y_1} = \frac{x_2}{y_2}\).
  • Examples:
  • Distance travelled and time taken (at constant speed).
  • Number of articles and their total cost.
  • Amount of work done and number of workers (assuming same efficiency).
  • Quantity of petrol and distance covered by a car.
  • Graphical Representation: Direct proportion ka graph hamesha origin se pass hone wali ek straight line hoti hai.
🧮సూత్రం

Direct Proportion Formula: If \(x\) and \(y\) are in direct proportion, then: \(\frac{x}{y} = k\) or \(\frac{x_1}{y_1} = \frac{x_2}{y_2}\)

💡సూచన

Direct proportion ke problems solve karte waqt, hamesha check karein ki ratio \(\frac{x}{y}\) constant hai ya nahi. Agar haan, toh direct proportion hai.

Solving Direct Proportion Problems

Direct proportion problems ko solve karne ke do main methods hain:

  1. Unitary Method:
  • Pehle ek unit ki value find karte hain.
  • Phir required units ki value calculate karte hain.
  • Example: Agar 5 pens ki cost ₹50 hai, toh 1 pen ki cost \(\frac{50}{5} = \text{₹}10\) hogi. 8 pens ki cost \(8 \times 10 = \text{₹}80\) hogi.
  1. Proportion Method:
  • Do quantities ke ratios ko equate karte hain.
  • \(\frac{x_1}{y_1} = \frac{x_2}{y_2}\) formula use karte hain.
  • Example: Agar 5 pens ki cost ₹50 hai, toh 8 pens ki cost \(C\) hogi. \(\frac{5}{50} = \frac{8}{C}\). Cross-multiply karke \(5C = 8 \times 50 \Rightarrow 5C = 400 \Rightarrow C = \text{₹}80\).
  • Steps to solve:
  1. Identify the two quantities involved.
  2. Determine if they are in direct proportion.
  3. Set up the proportion or use the unitary method.
  4. Solve for the unknown quantity.
🚧తప్పుడు అభిప్రాయం

Students often confuse direct and inverse proportion. Hamesha question ko carefully read karein aur determine karein ki ek quantity ke badhne par doosri badh rahi hai ya ghat rahi hai.

Inverse Proportions

Jab do quantities is tarah se related hoti hain ki ek ke badhne par doosri ghat jaati hai, aur ek ke ghatne par doosri badh jaati hai, toh unhe inverse proportion mein kaha jata hai.

  • Key Idea: Unka product hamesha constant rehta hai.
  • Agar \(x\) aur \(y\) inverse proportion mein hain, toh \(x \cdot y = k\) (jahan \(k\) ek constant hai).
  • Iska matlab hai, \(x_1 y_1 = x_2 y_2\).
  • Examples:
  • Speed of a vehicle and time taken to cover a fixed distance.
  • Number of workers and time taken to complete a fixed amount of work.
  • Number of pipes filling a tank and time taken to fill the tank.
  • Number of days food will last and number of people in a hostel.
  • Graphical Representation: Inverse proportion ka graph ek hyperbola hota hai, jo axes ko touch nahi karta.
🧮సూత్రం

Inverse Proportion Formula: If \(x\) and \(y\) are in inverse proportion, then: \(x \cdot y = k\) or \(x_1 y_1 = x_2 y_2\)

గుర్తుంచుకోండి

Inverse proportion mein, ek quantity double hone par doosri quantity half ho jaati hai, aur ek quantity triple hone par doosri one-third ho jaati hai.

Solving Inverse Proportion Problems

Inverse proportion problems ko solve karne ke bhi do main methods hain:

  1. Unitary Method (Modified):
  • Isme thoda alag tarike se sochte hain. Agar 1 worker ko 10 din lagte hain, toh 2 workers ko \(\frac{10}{2} = 5\) din lagenge.
  • Example: Agar 6 pipes ek tank ko 4 ghante mein bharte hain, toh 1 pipe ko \(6 \times 4 = 24\) ghante lagenge. Toh 8 pipes ko \(\frac{24}{8} = 3\) ghante lagenge.
  1. Product Method (Proportion Method):
  • Do quantities ke products ko equate karte hain.
  • \(x_1 y_1 = x_2 y_2\) formula use karte hain.
  • Example: Agar 6 pipes ek tank ko 4 ghante mein bharte hain, toh 8 pipes ko \(T\) ghante lagenge. \(6 \times 4 = 8 \times T \Rightarrow 24 = 8T \Rightarrow T = \frac{24}{8} = 3\) ghante.
  • Steps to solve:
  1. Identify the two quantities involved.
  2. Determine if they are in inverse proportion.
  3. Set up the product equation or use the modified unitary method.
  4. Solve for the unknown quantity.
💡సూచన

Inverse proportion mein, agar ek quantity increase ho rahi hai, toh doosri decrease hogi. Is logic ko hamesha cross-check karein apne answer ke saath.

Differentiating Direct and Inverse Proportions

Yeh samajhna bahut zaroori hai ki kab direct proportion use karna hai aur kab inverse proportion. Yahan kuch key differences diye gaye hain:

| Feature | Direct Proportion | Inverse Proportion | | :------------------ | :----------------------------------------------- | :----------------------------------------------- | | Relationship | One increases, other increases; one decreases, other decreases. | One increases, other decreases; one decreases, other increases. | | Mathematical Form | \(\frac{x}{y} = k\) (constant ratio) | \(x \cdot y = k\) (constant product) | | Graph | Straight line passing through origin | Hyperbola (does not touch axes) | | Real-life Example | Cost of items vs. quantity of items | Speed vs. time taken for a fixed distance |

  • Decision Making:
  • Question padho.
  • Identify karo kaun si do quantities involve hain.
  • Socho, agar ek quantity badhti hai, toh doosri ka kya hoga? Agar woh bhi badhegi, toh direct hai. Agar woh ghategi, toh inverse hai.
  • Uske according formula ya method apply karo.
గుర్తుంచుకోండి

Hamesha question ko carefully analyze karein. Kabhi-kabhi question mein hidden conditions ho sakti hain jo proportion ke type ko affect karti hain.

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