Question

Find and correct error in the following mathematical statement.
Substituting $x=-3$ in:
(a) $x^2+5x+4$ gives $(-3{)}^2+5(-3)+4=9+2+4=15$
(b) $x^2-5x+4$ gives $(-3{)}^2-5(-3)+4=9-15+4=-2$
(c) $x^2+5x$ gives $(-3{)}^2+5(-3)=-9-15=-24$

Answer 1

$\left(a\right)x^2+5x+4=(-3{)}^2+5(-3)+4=9-15+4=-2$

$\left(b\right)x^2-5x+4=(-3{)}^2-5(-3)+4=9+15+4=28$

$\left(c\right)x^2+5x=(-3{)}^2+5(-3)=9-15=-6$