Question

the value of $5x^{2}-11x + 18$ is when $x = 2.4$ and when $x=-3$.

Explanation:

Step1: Substitute $x = 2.4$

Substitute $x = 2.4$ into $5x^{2}-11x + 18$. First, calculate $5x^{2}=5\times(2.4)^{2}=5\times5.76 = 28.8$, $11x=11\times2.4 = 26.4$. Then $5x^{2}-11x + 18=28.8-26.4 + 18$.

Step2: Calculate the result for $x = 2.4$

$28.8-26.4+18=2.4 + 18=20.4$.

Step3: Substitute $x=-3$

Substitute $x = - 3$ into $5x^{2}-11x + 18$. Calculate $5x^{2}=5\times(-3)^{2}=5\times9 = 45$, $11x=11\times(-3)=-33$. Then $5x^{2}-11x + 18=45-(-33)+18$.

Step4: Calculate the result for $x=-3$

$45 + 33+18=96$.

Answer:

20.4; 96