Question

Find the value of the expressions for the given value of x.
(a) -3x + 2 for x = -1
(b) 3x^2 + 2x - 5 for x = - 4
(c) 9x - 5 for x = 3
(d) - 2x^2 + 3x - 2 for x = 2​

Answer 1

question :-

Find the value of the expressions for the given value of x.

(a) -3x + 2 for x = -1

(b) 3x^2 + 2x - 5 for x = - 4

(c) 9x - 5 for x = 3

(d) - 2x^2 + 3x - 2 for x = 2

Solution 1 :-

• put the value of x = -1 in the equation

$\mathsf{(a) \: - 3 x\: + \: 2}$

$\mathsf{: \longrightarrow \: - 3 \: \times \: - 1 + \: 2}$

$\mathsf{: \longrightarrow \: 3 \: + \: 2}$

$\mathsf{: \longrightarrow \: 5}$

Solution 2 :-

• Put the value of x = - 4 in the equation .

$\mathsf{(b) \: \:3x^2 + 2x - 5 }$

$\mathsf{: \longrightarrow \:3 \: ( - 4)^2 \: + \: 2 \: \times \: - 4 \: - 5 }$

$\mathsf{: \longrightarrow \:3 \: \times \: 16 \: - \: 8 \: - \: 5 }$

$\mathsf{: \longrightarrow \:48 \: - \: 8 \: - \: 5 }$

$\mathsf{: \longrightarrow \:40 \: - \: 5 }$

$\mathsf{: \longrightarrow \: 35 }$

Solution 3 :-

• Put the value of x = 3

$\mathsf{:\longrightarrow\:(c)\:9x\:-\:5}$

$\mathsf{: \longrightarrow \:9 \: \times \: 3\: - \: 5 }$

$\mathsf{: \longrightarrow \:27 \: - \: 5 }$

$\mathsf{:\longrightarrow\:22}$

Solution 4 :-

• Put the value of x = 2 in the equation .

$\mathsf{(d)\:- 2x^2 \: + \: 3x \: - \: 2 }$

$\mathsf{:\longrightarrow \:- 2(2)^2\:+\:3\:\times\: 2 \:- \:2}$

$\mathsf{:\longrightarrow \:-2\:\times\:4\:+\:6\:-\:2}$

$\mathsf{:\longrightarrow \:-\:8\:+\:6\:-\:2}$

$\mathsf{:\longrightarrow \:-\:10\:+\:6}$

$\mathsf{:\longrightarrow \:-\:4}$