Expand and simplify $(2x-3)(x-4)$. A student writes$$ (2x-3)(x-4)=2x^2-11x-12. $$ Identify the sig

Question

Expand and simplify $(2x-3)(x-4)$. A student writes$$ (2x-3)(x-4)=2x^2-11x-12. $$ Identify the sign error. Then use $x=0$ to show that the proposed expansion is incorrect.

Accepted Answer

(a) $2x^2-11x+12$. (b) $(-3)(-4)=+12$; at $x=0$, The original gives $12$, but the proposed answer gives $-12$.

Quadratic Functions, Equations and Inequalities

Quadratic Functions, Equations and Inequalities