Question

y=ax²+bx-c ,make a the subject of the formula

Answer 1

Explanations & Calculations

• Try isolating $\small a$ on one side by doing addition, subtraction and division where appropriate.

$\qquad\qquad \begin{aligned} \small y&=\small ax^2+bx-c\\ \small y+\color{red}{c}&=\small ax^2+bx-\cancel{c}+\cancel{\color{red}c}\cdots[\text{remove c}]\\ \small y+c&=\small ax^2+bx\\ \small y+c-\color{red} bx&=\small ax^2+\cancel{bx}-\cancel{\color{red} bx}\cdots[\text{remove bx}]\\ \small y-bx+c&=\small ax^2\\ \small \frac{y-bx+c}{\color{red} x^2}&=\small \frac{a\cancel{x^2}}{\cancel{\color{red}x^2}}\cdots\cdots\cdots[\text{remove}\,\,x^2]\\ \small a&=\small \frac{y-bx+c}{x^2} \end{aligned}$