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Maths Support: Expanding brackets
Expand the following to give a cubic in $y$.
$\simplify[std]{({a}y+{b})({c}y+{d})({p}y+{q})}=\;$question.score feedback.none Expected answer: .
Your answer should be a cubic in $y$ and should not include any brackets.
You can click on Show steps for more information, but you will lose one mark if you do so.
There is a video in Show steps which expands three brackets, but uses the variable $x$ rather than $y$.
There are many ways to expand an expression such as $(ay+b)(cy+d)(py+q)$.
One way is to expand the first two brackets, and then multiply the resulting quadratic in $y$ by $py+q$.
Hence:
\[\begin{eqnarray*} (ay+b)(cy+d)&=&ay(cy+d)+b(cy+d)\\&=&acy^2+ady+bcy+bd\\&=&acy^2+(ad+bc)y+bd\end{eqnarray*}\]
and then work out $(acy^2+(ad+bc)y+bd)(py+q)$.
See this video for more help:
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Using the method given by Show steps we first multiply out the first two brackets:
\[\begin{eqnarray*}\simplify[std]{ ({a}y+{b})({c}y+{d})}&=&\simplify[std]{{a}y*({c}y+{d})+{b}({c}y+{d})}\\&=&\simplify[std]{{a*c}y^2+{a*d}y+{b*c}y+{b*d}}\\&=&\simplify[std]{{a*c}y^2+{(a*d+b*c)}y+{b*d}}\end{eqnarray*}\]
And then multiply this by the third bracket:
\[\begin{eqnarray*}\simplify[std]{({a}y+{b})({c}y+{d})({p}y+{q})}&=&\simplify[std]{({a*c}y^2+{(a*d+b*c)}y+{b*d})({p}y+{q})}\\&=&\simplify[std]{{a*c}y^2({p}y+{q})+{(a*d+b*c)}y*({p}y+{q})+{b*d}({p}y+{q})}\\&=&\simplify[std]{{a*c*p}*y^3 +{a*c*q}*y^2+{p*(a*d+b*c)}y^2+{q*(a*d+b*c)}y+{b*d*p}y+{b*d*q}}\\&=&\simplify[std]{{a*c*p}y^3+{a*c*q+a*d*p+p*b*c}y^2+{a*d*q+b*c*q+b*d*p}y+{b*d*q}}\end{eqnarray*}\]
Expand the following to give quadratics in $x$.
$\simplify[std]{({a}x)({c}x+{d})}=\;$question.score feedback.none Expected answer: .
$\simplify[std]{({a1}x+{b1})({c1}x)}=\;$question.score feedback.none Expected answer: .
Your answers should be quadratics in $x$ and should not include any brackets.
You can click on Show steps to get more information, but you will lose one mark if you do so.
\[ax(cx+d)=acx^2+adx\]
1. Using the method given by Show steps we have:
\[\simplify[std]{ {a}x*({c}x+{d})}=\simplify[std]{{a*c}x^2+{a*d}x}\]
2.
\[\simplify[std]{ ({a1}x+{b1})*({c1}x)}=\simplify[std]{{a1*c1}x^2+{b1*c1}x}\]
Expand the following to give a quadratic in $x$.
$\simplify[std]{({a}x+{b})({c}x+{d})}=\;$question.score feedback.none Expected answer: .
Your answer should be a quadratic in $x$ and should not include any brackets.
There are many ways to expand an expression such as $(ax+b)(cx+d)$.
One way:
\[\begin{eqnarray*} (ax+b)(cx+d)&=&ax(cx+d)+b(cx+d)\\&=&acx^2+adx+bcx+bd\\&=&acx^2+(ad+bc)x+bd\end{eqnarray*}\]
Using the method given by Show steps we have:
\[\begin{eqnarray*}\simplify[std]{ ({a}x+{b})({c}x+{d})}&=&\simplify[std]{{a}x*({c}x+{d})+{b}({c}x+{d})}\\&=&\simplify[std]{{a*c}x^2+{a*d}x+{b*c}x+{b*d}}\\&=&\simplify[std]{{a*c}x^2+{(a*d+b*c)}x+{b*d}}\end{eqnarray*}\]
Expand the following to give a cubic in $w$.
$\simplify[std]{({p}w+{q})({a}w^2+{b}w+{c})}=\;$question.score feedback.none Expected answer: .
Your answer should be a cubic in $w$ and should not include any brackets.
One way to expand this is as follows:
$(pw+q)(aw^2+bw+c)=pw (aw^2+bw+c) +q(aw^2+bw+c)$ etc..
Or as $(pw+q)(aw^2+bw+c)=(aw^2+bw+c)(pw+q)$ we can expand it as:
$(aw^2+bw+c)(pw+q)=aw^2(pw+q)+bw(pw+q)+c(pw+q)$
Using the method given by Show steps:
\[\begin{eqnarray*}\simplify[std]{ ({p}w+{q})({a}w^2+{b}w+{c})}&=&\simplify[std]{{p}w*({a}w^2+{b}w+{c})+{q}({a}w^2+{b}w+{c})}\\&=&\simplify[std]{{a*p}w^3+{b*p}w^2+{c*p}w+{a*q}w^2+{q*b}w+{c*q}}\\&=&\simplify[std]{{a*p}w^3+{(a*q+b*p)}w^2+{b*q+c*p}w+{c*q}}\end{eqnarray*}\]
Expand the following to give a cubic in $z$.
$\simplify[std]{({a}z^2+{b}z+{c})({p}z+{q})}=\;$question.score feedback.none Expected answer: .
Your answer should be a cubic in $z$ and should not include any brackets.
$(az^2+bz+c)(pz+q)=az^2(pz+q)+bz*(pz+q)+c(pz+q)$ etc..
\[\begin{eqnarray*}\simplify[std]{ ({a}z^2+{b}z+{c})({p}z+{q})}&=&\simplify[std]{{a}z^2*({p}z+{q})+{b}*z*({p}z+{d})+{c}({p}z+{q})}\\&=&\simplify[std]{{a*p}z^3+{a*q}z^2+{b*p}z^2+{b*d}z+{c*p}z+{c*q}}\\&=&\simplify[std]{{a*p}z^3+{(a*q+b*p)}z^2+{b*d+c*p}z+{c*q}}\end{eqnarray*}\]
Expand the following to give a quartic in $z$.
$\simplify[std]{({a}z^2+{b}z+{c})({m}*z^2+{p}z+{q})}=\;$question.score feedback.none Expected answer: .
Your answer should be a quartic (degree 4 polynomial) in $z$ and should not include any brackets.
$(az^2+bz+c)(dz^2+pz+q)=az^2(dz^2+pz+q)+bz(dz^2+pz+q)+c(dz^2+pz+q)$ etc..
\[\begin{eqnarray*}\simplify[std]{ ({a}z^2+{b}z+{c})({m}z^2+{p}z+{q})}&=&\simplify[std]{{a}z^2*({m}z^2+{p}z+{q})+{b}*z*({m}z^2+{p}z+{q})+{c}({m}z^2+{p}z+{q})}\\&=&\simplify[std]{{a*m}z^4+{a*p}z^3+{a*q}z^2+{b*m}z^3+{b*p}z^2+{b*q}z+{c*m}z^2+{c*p}z+{c*q}}\\&=&\simplify[std]{{a*m}z^4+{a*p+m*b}z^3+{(a*q+c*m+b*p)}z^2+{b*q+c*p}z+{c*q}}\end{eqnarray*}\]
Simplify the following expression.
Simplify:
$\simplify[std]{({a}x+{b})({c}x+{d})-({a}x+{d})({c}x+{b})}=\;$question.score feedback.none Expected answer:
Do not include brackets in your answer.
Expanding the brackets we have:
\[\begin{eqnarray*}\simplify[std]{({a}x+{b})({c}x+{d})-({a}x+{d})({c}x+{b})}&=&(\simplify[std]{{a*c}x^2+{b*c+a*d}x+{b*d}})-(\simplify[std]{{a*c}x^2+{b*a+c*d}x+{b*d}})\\&=&\simplify[std]{{b*c+a*d}x-{b*a+c*d}x}\\&=&\var{(a-c)*(d-b)}x\end{eqnarray*}\]
$\simplify[std]{({a}x+{b}y)({c}x+{d}y)-({a}x+{d}y)({c}x+{b}y)}=\;$question.score feedback.none Expected answer:
Input $xy$ as $x*y$.
\[\begin{eqnarray*}\simplify[std]{({a}x+{b}y)({c}x+{d}y)-({a}x+{d}y)({c}x+{b}y)}&=&(\simplify[std]{{a*c}x^2+{b*c+a*d}x*y+{b*d}y^2})-(\simplify[std]{{a*c}x^2+{b*a+c*d}x*y+{b*d}y^2})\\&=&\simplify[std]{{b*c+a*d}x*y-{b*a+c*d}x*y}\\&=&\var{(a-c)*(d-b)}xy\end{eqnarray*}\]
Express the following expression as $ax+by$ for suitable integers $a$ and $b$.
Simplify $f(x,y)=\simplify[std]{{a}({b}x+{c}y)+{a1}x+{b1}y+{a2}({b2}x+{c2}y)}$
$f(x,y)=\;$question.score feedback.none Expected answer:
\[\begin{eqnarray*}f(x,y)&=&\simplify[std]{{a}({b}x+{c}y)+{a1}x+{b1}y+{a2}({b2}x+{c2}y)}\\&=&\simplify[std]{{a*b}x+{a*c}y+{a1}x+{b1}y+{a2*b2}x+{a2*c2}y}\\&=&\simplify[std]{{a*b}x+{a1}x+{a2*b2}x+{a*c}y+{b1}y+{a2*c2}y}\\&=&\simplify[std]{({a*b}+{a1}+{a2*b2})x+({a*c}+{b1}+{a2*c2})y}\\&=&\simplify[std]{{a*b+a1+a2*b2}x+{a*c+b1+a2*c2}y}\end{eqnarray*}\]
Score: 0/2 question.score feedback.none