UK Secondary (7-11)
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Non-monic quadratic equations
Lesson

So far most of what we have encountered with quadratics are those for which the coefficient of the $x^2$x2 term is a $1$1. These are called monic quadratics.

A non-monic quadratic is a quadratic that has a coefficient of the $x^2$x2 term not equal to $1$1. Here are some examples of non-monic quadratics:

$3x^2-2x$3x22x

$-2x^2+4x-5$2x2+4x5

$\frac{x^2}{2}-3x-10$x223x10

$7-1.6x+\sqrt{3}x^2$71.6x+3x2

We can use all the methods we have already seen to solve non-monic quadratic equations. The only difference is that some non-monic quadratics involve factorising or algebra that is a little more complicated. Methods that are particularly suited to non-monic quadratics are covered in non-monic factorisation.

Examples

Question 1

Solve for $x$x:

$11x^2=7x$11x2=7x

  1. Write all solutions on the same line, separated by commas.

Question 2

Solve the following equation by first factorising the left hand side of the equation. 

$5x^2+22x+8=0$5x2+22x+8=0

  1. Write all solutions on the same line, separated by commas.

Question 3

Solve the following equation for $b$b using the PSF method of factorisation: $15-11b-12b^2=0$1511b12b2=0

  1. Write all solutions in fraction form, on the same line separated by commas.

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