Simplify the expression 3 x 2- y 2- xy - xyz -2 xy -30 and find its value when x -6- y -7- and z -4-A- 3 x2-3 y2-x y z-x y-30 and 15B- 3 x 2-3 y 2- xyz - xy -30 and 15C- 3 x2-3 y2-x y z-5 x y-30 and 30D- 3 x 2-3 y 2- xyz -6 xy -30 and 7

The correct option is A 3x^2+3y^2+xyz+xy 30 and 153(x^2+y^2+xy)+xyz 2xy 30 nbsp; =3x^2+3y^2+3xy+xyz 2xy 30 =3x^2+3y^2+xyz+xy 30 ——(1) Substituting x=6, nb ...

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Byju's Answer

Standard VII

Mathematics

Value of an Expression

Simplify the ...

Question

Simplify the expression $3 (x^{2} + y^{2} + x y) + x y z - 2 x y - 30$ and find its value when $x = 6$ , $y = - 7$ , and $z = 4$ .

3 x^{2}

3 y^{2}

x y z

x y - 30

and

15

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3 x^{2}

3 y^{2}

x y z

x y - 30

and

15

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3 x^{2}

3 y^{2}

x y z

5 x y - 30

and

30

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3 x^{2}

3 y^{2}

x y z

6 x y - 30

and

7

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Solution

The correct option is A $3 x^{2}$ + $3 y^{2}$ + $x y z$ + $x y - 30$ and $15$
$3 (x^{2} + y^{2} + x y) + x y z - 2 x y - 30$
= $3 x^{2} + 3 y^{2} + 3 x y + x y z - 2 x y - 30$
= $3 x^{2} + 3 y^{2} + x y z + x y - 30$ ------(1)

Substituting $x = 6$ , $y = - 7$ , $z = 4$ in the equation (1),

$3 (6)^{2} + 3 (- 7)^{2} + (6) (- 7) (4) + (6) (- 7) - 30$
= $3 (36) + 3 (49) - 168 - 42 - 30$
= $108 + 147 - 168 - 42 - 30$
= $255 - 240$
= $15$

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Similar questions

Q. Simplify the expression 3(x + y + xy) + xyz - 2xy - 30 and find its value when x = 6 , y = -7, and z = 4.

Q. What should be subtracted from

3 x^{2} - 4 y^{2} + 5 x y + 20

to obtain

- x^{2} - y^{2} + 6 x y + 20

Q. If

x + y + z = x y z

, prove that

\frac{3 x - x^{3}}{1 - 3 x^{2}} + \frac{3 y - y^{3}}{1 - 3 y^{2}} + \frac{3 z - z^{3}}{1 - 3 z^{2}} = \frac{3 x - x^{3}}{1 - 3 x^{2}} \cdot \frac{3 y - y^{3}}{1 - 3 y^{2}} \cdot \frac{3 z - z^{3}}{1 - 3 z^{2}}

If x + y + z = xyz. Then

$\frac{3 x - x^{3}}{1 - 3 x^{2}}$ + $\frac{3 y - y^{3}}{1 - 3 y^{2}}$ + $\frac{3 z - z^{3}}{1 - 3 z^{3}}$ =

Q. In the expressions

x^{3} + 4 x y + 3 y^{2}

and

3 x^{2} + 5 x y

, which are the like terms?

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Simplify the expression 3(x2+y2+xy)+xyz−2xy−30 and find its value when x=6, y=−7, and z=4.

The correct option is A 3x2+3y2+xyz+xy−30 and 153(x2+y2+xy)+xyz−2xy−30 =3x2+3y2+3xy+xyz−2xy−30 =3x2+3y2+xyz+xy−30 ------(1) Substituting x=6, y=−7, z=4 in the equation (1), 3(6)2+3(−7)2+(6)(−7)(4)+(6)(−7)−30 =3(36)+3(49)−168−42−30 =108+147−168−42−30 =255−240 =15

Simplify the expression $3 (x^{2} + y^{2} + x y) + x y z - 2 x y - 30$ and find its value when $x = 6$ , $y = - 7$ , and $z = 4$ .