Quadratic Equations
New Zealand
Level 7 - NCEA Level 2
Variable substitution method
Interactive practice questions
We want to solve the following equation for $x$x: $x^4-34x^2+225=0$x4−34x2+225=0.
a
What substitution can we make to reduce this equation to a quadratic in the variable $p$p?
b
Substitute $p=x^2$p=x2 into the equation and solve for $p$p.
c
Now solve for $x$x using your previous answer as a reference. Write all solutions on the same line, separated by a comma.
Easy
4min
We want to solve the following equation for $x$x: $25x^4-65x^2+36=0$25x4−65x2+36=0.
Easy
7min
Consider the equation $81x^4-117x^2+36=0$81x4−117x2+36=0.
Easy
5min
Consider the equation $\left(4x+8\right)^2+16\left(4x+8\right)+48=0$(4x+8)2+16(4x+8)+48=0.
Easy
3min
Sign up to access Practice Questions
Get full access to our content with a Mathspace account