Question

Find and correct the errors in the following mathematical statements:

(a) $\frac{3x^2+1}{3x^2}=1+1=2$
(b) Substituting $x=-3$ in $x^2-5x+4$ gives $(-3{)}^2-5(-3)+4=9-15+4=-2$

Answer 1

(a) $\frac{3x^2+1}{3x^2}=1+1=2$

$\frac{3x^2+1}{3x^2}=\frac{3x^2}{3x^2}+\frac{1}{3x^2}=1+\frac{1}{3x^2}$

In RHS, instead of $1+1$ it should be 1 + $\frac{1}{3x^2}$.


(b) Substituting $x=-3$ in $x^2-5x+4$ gives $(-3{)}^2-5(-3)+4=9-15+4=-2$

When $x=-3$,
$x^2-5x+4$
$(-3{)}^2-5(-3)+4=9+15+4=28$

In $(-3{)}^2-5(-3)+4=9-15+4=-2$, instead of $-15$ it should be $+15$ in the RHS.