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Free study notes for CBSE & ICSE, Classes 6–12.

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MathematicsClass 10ICSE

Two Points Are All You Need to Write the Equation of Any Straight Line

Write equations of lines with the point-slope and two-point forms, find lines parallel or perpendicular to a given line through a point, find the median, altitude and perpendicular bisector of a triangle, and work out intercepts and intersections.

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MathematicsClass 10ICSE

The Steepness of Any Road Can Be Captured by One Number Called Its Gradient

Find the slope of a line from two points, from its inclination and from its equation, use slopes to test for parallel and perpendicular lines, read the gradient and intercept from y = mx + c, and check whether three points are collinear.

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MathematicsClass 10ICSE

Find the Balance Point of Any Triangle by Averaging Its Corners

Use the section formula to find a point dividing a segment in a ratio, find the ratio in which a point or an axis divides a segment, use mid-points to find missing vertices, and locate the centroid and points of trisection.

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MathematicsClass 10ICSE

Why a Temple's Reflection in a Pond Flips Upside Down but Not Left to Right

Find the image of a point reflected in the x-axis, the y-axis, the origin and the lines x = a and y = a, spot invariant points, name the mirror line from a point and its image, and plot successive reflections to identify the figure formed.

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MathematicsClass 10ICSE

Why Folding a Sheet of Paper in Half Again and Again Makes It Thick So Fast

Test whether a sequence is a geometric progression, find its nth term and which term equals a value, add its first n terms, and use the geometric mean in growth and depreciation problems.

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MathematicsClass 10ICSE

Why Adding a Pattern Forwards and Backwards Gives Its Sum in One Line

Find the sum of an AP with both sum formulas, work out how many terms give a stated sum, recover any term from the sums, and solve savings, instalment and stacking problems.

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MathematicsClass 10ICSE

One Formula Finds the 100th Term of a Pattern Without Listing the First 99

Test whether a sequence is an arithmetic progression, use the nth term formula, count the terms of a finite AP and find which term equals a value, and work out the first term and common difference from two terms.

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MathematicsClass 10ICSE

Why A Times B Is Usually Not the Same as B Times A for Matrices

Learn when two matrices can be multiplied and what order the product has, multiply 2x2 and column matrices, verify that matrix multiplication is not commutative but is distributive, and solve AX = B and A² = kA + mI.

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MathematicsClass 10ICSE

A Matrix Is a Neat Table of Numbers That Follows Its Own Arithmetic

Find the order of a matrix and name row, column, square, zero and identity matrices, use equality of matrices to find unknowns, add and subtract 2x2 matrices, and multiply by a number to solve simple matrix equations.

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MathematicsClass 10ICSE

Find a Polynomial's Remainder Without Doing Any Long Division

Use the Remainder Theorem to find remainders in one step, test factors with the Factor Theorem, find unknown coefficients from factor and remainder conditions, and factorise cubic polynomials completely.

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MathematicsClass 10ICSE

A Two-Line Trick Solves Equations That Look Too Messy to Cross-Multiply

Learn invertendo, alternendo, componendo and dividendo, use componendo and dividendo to solve equations for x, handle equations with surds and cubes, and prove proportion identities with the k-method.

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MathematicsClass 10ICSE

Why the Mean Proportional Between 4 and 9 Is 6, Not 6.5

Work out compounded, duplicate, sub-duplicate, triplicate and sub-triplicate ratios, divide quantities in a ratio and handle ratios that change, find fourth, third and mean proportionals, and test continued proportion.

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MathematicsClass 10ICSE

When a Word Problem Gives Two Answers, How Do You Know Which One Is Real?

Turn word problems on numbers, ages, two-digit numbers, trains and boats, fields, paths and pipes into quadratic equations, solve them, and learn how to reject the root that cannot fit the situation.

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MathematicsClass 10ICSE

One Number Tells You Whether a Quadratic Has Two Roots, One Root or None

Use the discriminant to decide the nature of roots without solving, find the value of k that gives equal roots, find an unknown coefficient from a known root, and solve quadratics with surd or letter coefficients.

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MathematicsClass 10ICSE

Every Quadratic Equation Can Be Solved With One Formula, Even When Factorising Fails

Recognise a quadratic equation and write it in standard form, solve it by splitting the middle term, use the quadratic formula with correct rounding, and handle equations with fractions or reciprocals that reduce to quadratics.

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MathematicsClass 10ICSE

Why Multiplying by a Negative Number Flips an Inequality Sign

Solve linear inequations and write the solution set for natural numbers, whole numbers, integers and real numbers, show it on a number line, handle combined inequations, and find greatest or smallest values in word problems.

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MathematicsClass 10ICSE

Why a 10% Dividend Does Not Mean a 10% Return on Your Money

Tell face value from market value, count how many shares an investment buys at par, at a premium or at a discount, calculate dividend income and percentage return, compare investments, and solve inverse share problems.

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MathematicsClass 10ICSE

Why Saving ₹1000 a Month Earns Less Interest Than Depositing ₹12000 at Once

See where the recurring deposit interest formula comes from, calculate interest and maturity value step by step, and work backwards to find the monthly instalment, the rate of interest or the number of months.

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MathematicsClass 10ICSE

GST Is Collected at Every Step, Yet Only the Last Buyer Really Pays It

Calculate input tax credit and net GST at each stage from manufacturer to retailer, find the total GST reaching the government, fill in a GST invoice with items at different rates, and solve problems that combine discount, profit and GST.

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MathematicsClass 10ICSE

Why Half the GST on a Local Bill Goes to the State and Half to the Centre

Work out CGST, SGST and IGST on any bill, find the price paid after a discount, calculate GST when a shopkeeper makes a profit or loss, and reverse the working to find a list price, cost price or GST rate from the tax paid.

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BiologyClass 10ICSE

The Same Gases That Keep Earth Warm Could Overheat It if They Keep Rising

Understand the greenhouse effect and global warming, see how acid rain forms and how the ozone layer is thinned, learn how pollution affects climate, health and wildlife, and review practical measures from CNG to sewage treatment.

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BiologyClass 10ICSE

Why a Banana Peel Vanishes in Weeks but a Plastic Bottle Stays for Generations

Learn what pollution is and where air, water and soil pollutants come from, understand biomedical waste, radiation and noise pollution, tell biodegradable from non-biodegradable waste, and see why plastics, glass, thermocol and DDT cause lasting harm.

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BiologyClass 10ICSE

Falling Death Rates, Not Rising Birth Rates, Set Off the Population Boom

Learn what demography, population density, birth rate, death rate and growth rate mean with worked calculations, why human numbers rose so sharply, what problems a population explosion creates, and how population education and family planning methods help.

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BiologyClass 10ICSE

Why Colour Blindness Turns Up Far More Often in Boys Than in Girls

Tell autosomes from sex chromosomes, see how an XX and XY cross decides whether a baby is a boy or a girl, follow the inheritance of haemophilia and colour blindness, and understand how mutation and variation differ.

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