Question

evaluate 3x^2-4x -5 if x= -2​

Answer 1

$3x {}^{2} - 4x - 5$

$x = ( - 2)$

Put ( - 2 ) in x place

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

$= 3(4) + 8 - 5$

$= 12 + 8 - 5$

$= 20 - 5$

$= 15$

Be Brainly!

Answer 2

From the given question the correct answer is:

$3x^2-4x -5$= 15

Given:

$3x^2-4x -5$

x=-2

To find:

$3x^2-4x -5$=?

Solution:

we evaluate the equation

given that,

x = -2

so, put the value in expression.

$3x^2-4x -5$

x=-2

we will use the BODMAS rule

B bracket

O of or order

D Division

M multiplication

A  addition

S subtraction

$=3x^2-4x -5\\\\=3\times -2^{2} -4\times-2-5\\=3\times4+8-5\\\\=12+3\\=15$

Hence, $3x^2-4x -5$= 15