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IB Maths AI 2.3 Definitions

This page contains our IB Maths AI definitions for 2.3. By learning each one of these definitions, you will fully cover the content for IB Maths AI 'Introduction to modelling functions'.

axis of symmetry

The vertical line through the vertex of a quadratic, with equation x=b2ax=-\frac{b}{2a} for f(x)=ax2+bx+cf(x)=ax^{2}+bx+c.

gradient

The coefficient aa in y=ax+by=ax+b, giving the predicted change in yy when xx increases by 11.

horizontal asymptote

A horizontal line y=cy=c that an exponential graph approaches as xx increases or decreases, for models such as f(x)=kax+cf(x)=ka^{x}+c or f(x)=kerx+cf(x)=ke^{rx}+c.

quadratic model

A function of the form f(x)=ax2+bx+cf(x)=ax^{2}+bx+c with a0a \neq 0, whose graph is a parabola and is suitable when there is a turning point.

roots

Values of ww that satisfy an equation of the form wn=zw^n=z; for z=rcisθz=r\operatorname{cis}\theta, the nnth roots are wk=rncis(θ+2kπn)w_k=\sqrt[n]{r}\operatorname{cis}\left(\frac{\theta+2k\pi}{n}\right) for k=0,1,,n1k=0,1,\dots,n-1.

vertex

A point in a graph.

vertical asymptote

A vertical line that a graph approaches but never reaches; for inverse variation models with n<0n \lt 0 in f(x)=axnf(x)=ax^{n}, the line x=0x=0 (the yy-axis) is a vertical asymptote.

y-intercept

The point where a line crosses the yy-axis, found by setting x=0x=0 in the equation of the line.

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