Math tutors are valuable for children of all ages. Sign up for math tutoring and get started with our proven system to increase math knowledge.
The short version Parallel lines are lines in the same flat plane that never meet, no matter how far you extend them. They stay the same distance apart everywhere. The symbol is ||. “AB || CD” means line AB is parallel to line CD. On a graph, parallel lines have the same slope and different…
The short version A positive slope goes up as you read the graph left to right. A negative slope goes down left to right. Slope = rise ÷ run = (y2 – y1) ÷ (x2 – x1). If the answer is above zero, the slope is positive. If it’s below zero, it’s negative. A horizontal…
The short version Perpendicular lines are two lines that cross at a right angle, 90°. Where they meet, they form four right angles. The symbol is ⊥. “AB ⊥ CD” means line AB is perpendicular to line CD. In drawings, a small square in the corner marks the right angle. Everyday examples: the corner of…
The short version Skew lines are two lines that never touch and aren’t parallel. That can only happen in 3D space, because the lines sit in different planes. To check a pair, ask three questions: Do they meet? Do they point the same way? Could one flat sheet hold both? Skew means no, no, and…
The short version The FOIL method multiplies two binomials by multiplying the First terms, the Outer terms, the Inner terms, and the Last terms, then adding the four results. Example: (x + 4)(x + 5) = x² + 5x + 4x + 20 = x² + 9x + 20. FOIL is a shortcut for the…
The short version The reciprocal of a number is what you multiply it by to get 1. For a fraction, flip it: the reciprocal of 3/4 is 4/3. For a whole number, put it under 1: the reciprocal of 6 is 1/6. For a mixed number or decimal, turn it into a fraction first, then…
The short version The triangle angle sum theorem says the three interior angles of any triangle add up to 180°. To find a missing angle, subtract the two known angles from 180. With angles of 48° and 67°, the third is 180 – 48 – 67 = 65°. For “solve for x” problems, add the…
The short version A multiple of a number is what you get when you multiply it by a whole number. The multiples of 7 are 7, 14, 21, 28, 35, and so on forever. To check if one number is a multiple of another, divide. If there’s no remainder, it’s a multiple: 91 ÷ 7…
The short version The dividend is the number being divided. The divisor is the number you divide by. In 20 ÷ 4 = 5, 20 is the dividend, 4 is the divisor, and 5 is the quotient (the answer). When it doesn’t divide evenly, the leftover is the remainder: 47 ÷ 6 = 7 R…
The short version The numerator is the top number of a fraction and counts how many parts you have. The denominator is the bottom number and tells you how many equal parts make one whole. Memory trick: Denominator starts with D, and D is for Down. The denominator is the number down below. The denominator…