2.3.7 · Maths › Coordinate Geometry
Intuition Ek sentence mein picture
Intercept simply woh jagah hai jahan ek line (ya curve) ek axis ko cross karti hai . Kisi axis ko cross karne ke liye ek coordinate zero hona chahiye — kyunki axis par "doosri direction mein koi distance nahi hoti." Yahi ek fact har intercept formula ko generate karta hai .
Intuition Kyun care karein?
Do points ek straight line fix kar dete hain. Kisi bhi line par find karne ke liye sabse aasaan do points uske axis crossings hote hain, kyunki un points par ek coordinate forced hoti hai 0 par, jo equation ki ek poori term ko khatam kar deti hai. Toh intercepts woh sab se sasta data hain jo aap ek line se nikal sakte hain — fast graphing ke liye perfect (80/20 move).
x-intercept woh x -value hai jahan ek graph x-axis se milta hai. x-axis par har point par y = 0 hota hai. Toh ise find karne ke liye, set y = 0 aur x ke liye solve karo . Woh point hota hai ( x 0 , 0 ) .
y-intercept woh y -value hai jahan ek graph y-axis se milta hai. y-axis par har point par x = 0 hota hai. Toh ise find karne ke liye, set x = 0 aur y ke liye solve karo . Woh point hota hai ( 0 , y 0 ) .
Common mistake Steel-man: "x-intercept means set x = 0"
Kyun sahi lagta hai: word "x" wahan hai, toh students x = 0 set kar dete hain. Kyun galat hai: x-intercept x-axis par hota hai, aur x-axis par points ka y = 0 hota hai, x = 0 nahi. Fix / memory hook: intercept ka naam us axis ke naam par hai jise woh touch karta hai, aur us axis par doosra variable gayab ho jaata hai. x-intercept ⇒ y ko khatam karo.
Ek general line A x + B y = C se shuru karo (jahan A , B , C = 0 ).
Step 1 — x-intercept find karo. Set y = 0 :
A x = C ⟹ x = A C .
Yeh step kyun? x-axis par y = 0 hota hai, toh B y term gayab ho jaati hai aur sirf x bachta hai.
Step 2 — y-intercept find karo. Set x = 0 :
B y = C ⟹ y = B C .
Yeh step kyun? y-axis par x = 0 hota hai, toh A x term khatam ho jaata hai.
Step 3 — inhe naam do. Maano a = A C (x-intercept) aur b = B C (y-intercept).
Step 4 — a , b use karke equation dobara banao. A x + B y = C ko C se divide karo:
C A x + C B y = 1 ⟹ C / A x + C / B y = 1.
Toh hum pahunch jaate hain intercept form par:
Intuition Slope-intercept se link
y = m x + c se, x = 0 set karne par y = c milta hai, toh c literally y-intercept hai . y = 0 set karne par x = − c / m milta hai, jo x-intercept hai. Isliye y = m x + c mein c ko intercept kaha jaata hai.
Worked example Example 1 — line
2 x + 3 y = 12
Forecast: compute karne se pehle intercepts guess karo. (Try karo!)
x-intercept: set y = 0 : 2 x = 12 ⇒ x = 6 . Point ( 6 , 0 ) .
Kyun? y-axis ka term 3 y gayab ho jaata hai.
y-intercept: set x = 0 : 3 y = 12 ⇒ y = 4 . Point ( 0 , 4 ) .
Kyun? x term khatam ho jaata hai.
Intercept form se verify karo: 6 x + 4 y = 1 . 12 se multiply karo: 2 x + 3 y = 12 ✓.
Worked example Example 2 — ek curve, line nahi:
y = x 2 − 5 x + 6
x-intercepts (set y = 0 ): x 2 − 5 x + 6 = 0 ⇒ ( x − 2 ) ( x − 3 ) = 0 ⇒ x = 2 , 3 . Points ( 2 , 0 ) , ( 3 , 0 ) .
Yeh step kyun? Equation ke roots hi x-axis crossings hote hain — geometrically "root" ka yahi matlab hai.
y-intercept (set x = 0 ): y = 0 − 0 + 6 = 6 . Point ( 0 , 6 ) .
Kyun? Bas x = 0 plug karo; constant term 6 hamesha ek polynomial ka y-intercept hota hai.
Worked example Example 3 — intercepts ko ulta padhna
Ek line ka x-intercept 4 aur y-intercept − 2 hai. Iska equation find karo.
Intercept form use karo: 4 x + − 2 y = 1 .
4 se multiply karo: x − 2 y = 4 .
Kyun? Humein bataya gaya hai a = 4 , b = − 2 , toh intercept form direct plug-and-go route hai.
Common mistake Steel-man: "a line through the origin has intercepts I can use in
a x + b y = 1 "
Kyun sahi lagta hai: har line ki crossings hoti hain. Kyun galat hai: y = 2 x jaisi line ( 0 , 0 ) se guzarti hai, toh a = 0 aur b = 0 — aap zero se divide kar rahe hote. Fix: intercept form ke liye a = 0 , b = 0 zaroori hai; origin lines ke liye bas y = m x use karo.
x-intercept find karne ke liye kaun sa variable zero set karte hain? y = 0 (point x-axis par hota hai jahan y = 0 ).
y-intercept find karne ke liye kaun sa variable zero set karte hain? x = 0 .
Intercepts a aur b wali line ki intercept form batao. a x + b y = 1 .
y = m x + c mein kaun sa number y-intercept hai?c .
2 x + 3 y = 12 ka x-intercept?6 , yaani point ( 6 , 0 ) .
y = x 2 − 5 x + 6 ka y-intercept?6 , yaani point ( 0 , 6 ) .
Origin se jaane wali line intercept form mein kyun nahi likhi ja sakti? Dono intercepts 0 hain, toh a x + b y zero se divide karta hai.
Geometrically, y = f ( x ) ke x-intercepts kya hote hain? f ( x ) = 0 ke real roots.
Recall Feynman: ek 12-saal ke bacche ko explain karo
Socho ek graph paper par ek road bani hai. Graph paper par do badi roads hain: seedhi wali (x-axis) aur upar-neeche wali (y-axis). Intercept bas woh jagah hai jahan tumhari line un badi roads mein se kisi ek ko touch karti hai. Jab tumhari line seedhi road ko touch karti hai, uska "upar ka amount" (y ) zero hota hai — toh y = 0 karo aur dekho woh kahan jaati hai. Jab woh upar-neeche wali road ko touch karti hai, uska "sideways amount" (x ) zero hota hai — toh x = 0 karo. Bas yahi poora trick hai: jahan road ko touch karo, wahan doosri direction zero set karo.
"Ek road touch karo ⇒ DOOSRA zero hoga."
x-intercept x-axis ko touch karta hai ⇒ set y = 0 . y-intercept y-axis ko touch karta hai ⇒ set x = 0 .
Slope-Intercept Form (y = mx + c) — c hi y-intercept hai.
General Equation of a Line (Ax + By = C) — woh source jahan se humne intercept form derive ki.
Roots of a Quadratic — parabola ke x-intercepts uske roots hote hain.
Graphing Straight Lines — do intercepts use karke fast plot karo.
Distance & Coordinates on the Cartesian Plane — kyun "axis par hona" ek coordinate ko 0 force karta hai.
On an axis one coord is zero
Intercept form x/a + y/b = 1
Slope-intercept y = mx + c
Mistake: set x=0 for x-intercept
Fast graphing with 2 points