Question

Find and correct the errors in the following mathematical statement, Substituting $x=-3$ in
$x^2+5x+4$ gives $(-3{)}^2+5(-3)+4=9+2+4=15$

Answer 1

When we substitute $x=-3$ in $x^2+5x+4$

$x^2+5x+4$

$=(-3{)}^2+5(-3)+4$

$=9-15+4$

$=13-15$

$=-2$

Now, lets observe the given substitution,

$(-3{)}^2+5(-3)+4$

$=9+2+4=15$

Here, $5(-3)=-15$ not $2$.

Error: Subtraction is done instead of multiplication.