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Online Tutorial -
CG50: Solve Quadratic Equations

Video Transcript


In this tutorial we're looking at how to use the CG50 to solve quadratic equations. To work along with this tutorial you may find it easiest to reset the calculator before starting so that your screen matches the one in the video.

From the main menu choose equation mode by pressing A. If your screen doesn't look like this, then press exit as many times as needed until it does. Choose polynomial and then choose degree 2. And then type the values A=3, B=-8 and C=4. These are the coefficients of X squared, of X and the constant term. These are the values of a, b and c that you would use if you were using the quadratic formula. Press solve and the two roots appear. Move the cursor up and down to see each root and the SD key will give the root in a different form. To solve another equation, press repeat and then enter A=1, B=8 and C=5. You can simply overtype the existing values.

And then solve and the matrix gives decimal values for the roots, with the surd form also given. Scroll down to see the other root in surd form. The SD key will give the decimal answer to more decimal places. Again, press repeat for the next equation.

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This equation has been chosen as it has no real roots. How your calculator deals with this depends on the settings you've chosen. Notice the default setting after resetting the calculator is real. Type A=1, B=2 and C=6 and then solve. An error screen appears indicating there are no real roots and for many people that is all they need to know. To find out more see our other resources on solving equations with complex roots.

Moving on from quadratics, you might want to explore, using equation mode to solve cubic and higher polynomial equations as well. You just have to use exit as many times as you needed to go back to previous menu screens and make different choices.

You can find additional resources at education.casio.co.uk

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