Algebra: Substitution Practice 1
Substitution is very easy if you follow the three key steps carefully, and doing so can help you achieve 100% accuracy. To strengthen your understanding, here are 5 practice questions for you to try.
Related Lessons:
Practice 1 - Question 1
Practice 1 - Question 2
Given that \(x=3\left(y-2z\right)\), find the value of \(z\) when \(x=21\) and \(y=42\).
Solution:
\[
\begin{align*}
\left(21\right)&=3\left(\left(42\right)-2z\right)\\
\frac{21}{3}&=42-2z\\
2z&=42-7\\
z&=\frac{35}{2}\\
&=17.5
\end{align*}
\]
Practice 1 - Question 3
Given that \(y+\frac{3a}{b}=3x+\frac{14c}{5}\), find the value of c given that \(y=4\), \(a=2\), \(b=-3\) and \(x=-4\).
Solution:
\[
\begin{align*}
\left(4\right)+\frac{3\left(2\right)}{\left(-3\right)}&=3\left(-4\right)+\frac{14c}{5}\\
2&=-12+\frac{14c}{5}\\
\frac{14c}{5}&=2+12\\
c&=14\times\frac{5}{14}\\
&=5
\end{align*}
\]
Practice 1 - Question 4
Given that \(c=-5\), \(d=3\) and \(e=2\), find the value of \(c-2d+5e\).
Solution:
\[
\begin{align*}
c-2d+5e&=\left(-5\right)-2\left(3\right)+5\left(2\right)\\
&=-1
\end{align*}
\]
Practice 1 - Question 5
Given that \(a=-2\), \(b=3\) and \(c=5\), evaluate \(\left(a-b\right)^2\times\left(c+ab\right)^3\).
Solution:
\(\left(a-b\right)^2\times\left(c+ab\right)^3\)
\(=\left(\left(-2\right)-\left(3\right)\right)^2\times\left(\left(5\right)+\left(-2\right)\left(-3\right)\right)^3\)
\(=-25\)
Step By Step Full Solution
Below is the full solution for the above 5 questoins for students who needed step by step guidence.