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Which of these expressions equal 15 when x = and y=3? Circle
all that apply.
4 (2y-4x)-1
(x²+1)+2x+3y
4x²+2y³-10
xy+3+20x

Sagot :

Answer:

Option 1: 4(2y - 4x) -1

Step-by-step explanation:

Hello!

Given:

  • x = 0.5
  • y = 3

Plug in the values for x and y into each equation and see which one outputs 15.

4(2y - 4x) -1

  • 4(2(3) - 4(0.5)) - 1
  • 4(6 - 2) - 1
  • 4(4) - 1
  • 16-1
  • 15

(x² + 1) + 2x + 3y

  • (0.5² + 1) + 2(0.5) + 3(3)
  • 1.25 + 1 + 9
  • 11.25

4x²+2y³-10

  • 4(0.5²) + 2(3³) - 10
  • 4(0.25) + 2(27) - 10
  • 1 + 54 - 10
  • 55 - 10
  • 45

xy+3+20x

  • (0.5)(3) + 3 + 20(0.5)
  • 1.5 + 3 + 10
  • 4.5 + 10
  • 14.5

The only option that works is the first option.

Answer:

[tex]4 (2y-4x)-1[/tex]

Step-by-step explanation:

Given:

  • [tex]x =\dfrac{1}{2}[/tex]
  • [tex]y=3[/tex]

To find which expressions equal 15, substitute the given values of x and y into the expressions and evaluate:

[tex]\begin{aligned}4(2y-4x)-1 &= 4 \left(2(3)-4 \left(\dfrac{1}{2}\right)\right)-1\\& = 4 \left(6-2\right)-1\\& = 4 \left(4\right)-1\\& = 16-1\\& = 15\\\end{aligned}[/tex]

[tex]\begin{aligned}(x^2+1)+2x+3y & = \left(\left(\dfrac{1}{2}\right)^2+1\right)+2 \left(\dfrac{1}{2}\right)+3(3)\\& = \left(\left\dfrac{1}{4}+1\right)+1+9\\& = \dfrac{5}{4}+1+1+9\\& = \dfrac{45}{4}\end{aligned}[/tex]

[tex]\begin{aligned}4x^2+2y^3-10 & = 4\left(\dfrac{1}{2}\right)^2+2(3)^3-10\\& = 4\left(\dfrac{1}{4}\right)+2(27)-10\\& = 1+54-10\\& = 45\end{aligned}[/tex]

[tex]\begin{aligned}xy+3+20x & = \left(\dfrac{1}{2}\right)(3)+3+20\left(\dfrac{1}{2}\right)\\& = \dfrac{3}{2}+3+10\\& = \dfrac{29}{2}\end{aligned}[/tex]

Therefore, the only expression that equals 15 is:

  [tex]4(2y-4x)-1[/tex]