# How to Use GeoGebra's CAS Tools

##### What are Tools?
[size=100]GeoGebra provides a [i]Toolbar [/i]with a selection of [i]Tools [/i]specific for the CAS [i]View[/i]. You may [b]activate a [/b][i][b]Tool[/b] [/i]by clicking on the button showing the corresponding icon.[br][br][b]Task[/b]: Solve an equation using the [icon]/images/ggb/toolbar/mode_solve.png[/icon] [i]Solve[/i] tool[/size][list=1][*][size=100]Type the equation [code]3x + 1 = 10[/code] into the [i]CAS Input[/i].[/size][/*][*][size=100]Select the [img]https://wiki.geogebra.org/uploads/thumb/a/a9/Mode_solve.svg/16px-Mode_solve.svg.png[/img] [i]Solve[/i] tool from the [i]CAS View Toolbar[/i].[br][u]Note[/u]: The equation is solved and the solution is shown underneath the equation.[/size][/*][/list]
##### What are Tooltips?
[size=100]If you select a [i]Tool[/i], a [b][i]Tooltip [/i]appears[/b] explaining how to use this [i]Tool[/i].[br][u]Hint[/u]: Click on a [i]Tooltip[/i] in order to open a web page providing help for the selected [i]Tool[/i].[br][br][/size][b]Task[/b]: Factorize the term [code](x² - 4)[/code] using the [icon]/images/ggb/toolbar/mode_factor.png[/icon] [i]Factor [/i]tool.

# The CAS Tools

##### The CAS View Toolbar
[size=100]The [i]CAS View Toolbar[/i] provides a range of [i]CAS Tools[/i] that can be operated with your pointer. They allow you to evaluate input and perform calculations. [br][br][img]https://wiki.geogebra.org/uploads/thumb/c/c3/Toolbar-CAS.png/315px-Toolbar-CAS.png[/img][br][/size][u][br]Note[/u]: Always enter your input before you select the desired [i]CAS Tool[/i]. In this way, the tool can be applied directly to your input.
##### Familiarize yourself with GeoGebra's CAS Tools
[table][tr][td][size=100]﻿1.[/size][/td][td][size=100][icon]/images/ggb/toolbar/mode_keepinput.png[/icon]﻿[/size][/td][td][size=100]Type [code]f(x) := x ^ 2 - 4 [/code]into the [i]CAS Input [/i]and select the [i]Keep Input[/i] tool in order to define a quadratic polynomial.[br][/size][/td][/tr][tr][td][size=100]﻿2.[/size][/td][td][size=100]﻿[icon]/images/ggb/toolbar/mode_factor.png[/icon][/size][/td][td][size=100]﻿Type [code]f(x)[/code] into the next row of the [i]CAS View[/i] and select the [i]Factor[/i] tool to find the factors of the function.[br][/size][/td][/tr][tr][td][size=100]﻿3.[/size][/td][td][size=100]﻿[icon]/images/ggb/toolbar/mode_derivative.png[/icon][/size][/td][td][size=100]﻿Enter [code]f(x)[/code] into the next row and select the [i]Derivative[/i] tool to calculate the derivative of the function.[br][/size][/td][/tr][tr][td][size=100]4.[/size][/td][td][size=100][icon]https://wiki.geogebra.org/uploads/thumb/4/4d/Algebra_hidden.png/40px-Algebra_hidden.png[/icon][/size][/td][td][size=100][u]Hint[/u]: You can display the graph of the derivative function by clicking on the [i]Show / Hide[/i] icon next to its equation.[br][/size][/td][/tr][/table][size=100][u][br]Hint[/u]: [size=100]You might want to [img]https://wiki.geogebra.org/uploads/thumb/8/81/Menu-view-refresh-views.svg/16px-Menu-view-refresh-views.svg.png[/img] reset your construction in order to try out more[/size] [i]CAS Tools[/i].[br][/size]
##### Selected CAS Tools you might want to try out as well
[table][tr][td][size=100]﻿[icon]/images/ggb/toolbar/mode_evaluate.png[/icon][/size][/td][td][size=100][b]Evaluate﻿[/b][br]Use the [i]Evaluate[/i] tool in order to calculate and simplify the input in a symbolic way.[/size][/td][/tr][tr][td][size=100]﻿[icon]/images/ggb/toolbar/mode_numeric.png[/icon][/size][/td][td][size=100][b]Numeric﻿[/b][br]Use the [i]Numeric[/i] tool in order to calculate the input numerically and get the result in decimal notation.[/size][/td][/tr][tr][td][size=100]﻿[icon]/images/ggb/toolbar/mode_keepinput.png[/icon][/size][/td][td][size=100][b]Keep Input[/b][br]Use the [i]Keep Input[/i] tool in order to keep and check the input. [br][u]Hint[/u]: This is very useful if you don’t want your input to be simplified automatically.[/size][/td][/tr][tr][td][size=100][icon]/images/ggb/toolbar/mode_expand.png[/icon]﻿[/size][/td][td][size=100][b]Expand[/b][br]Use the [i]Expand [/i]tool in order to expand an expression [br][u]Example[/u]: Applying the [i]Expand [/i]tool to the input [code]2*(a + b)[/code] results in the output [i]2a + 2b[/i].[/size][/td][/tr][tr][td][size=100]﻿[icon]/images/ggb/toolbar/mode_substitute.png[/icon][/size][/td][td][size=100][b]Substitute[/b][br]Use the [i]Substitute [/i]tool in order substitute numbers for variables in an expression. After applying the tool to an expression, a dialog window appears, allowing you to enter the values you want to substitute.  [/size][/td][/tr][/table]