Substitution Flashcards

All 6 cards in this deck

What does it mean to substitute into a formula?

Replace each letter with its given numerical value and work out the answer.

What are the steps to substitute a value into a formula?

e.g. find $T$ when $m = 2$ in $T = 4m^2 - 11$

1. Replace the letter with its value: $4 \times 2^2 - 11$
2. Work out powers first: $4 \times 4 - 11$
3. Then multiply, then add/subtract: $T = 5$

When substituting a negative value into a squared term, what must you do?

e.g. $w = 40 - t^2$ with $t = -5$

Put the negative number in brackets before squaring: $40 - (-5)^2 = 40 - 25 = 15$.

True or false? If $m = -3$ then $m^2 = -9$.

False. $m^2 = (-3) \times (-3) = 9$, since a negative times a negative is positive.

In the formula $v = u + at$, what does $at$ tell you to do?

Multiply $a$ by $t$, then add the result to $u$.
e.g. $a = -3$, $t = \frac{1}{2}$ gives $at = -\frac{3}{2}$.

In $T = 4m^2 - 11$, which operation is done first when substituting?

The power: square $m$ first, then multiply by $4$, then subtract $11$.