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3 years ago

From MATH workbook.

Mathematics

1 answer:

bixtya [17]3 years ago

5 0

Step-by-step explanation:

3^5= 243

3^-1 = 0.3333333

243* 0.33= 80.19

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Use all four operations and at least one exponent to write an expression that has a value of 100.

OleMash [197]

Answer: 5 to the 2 power x4+100 divide by 2

Step-by-step explanation:

3 0

3 years ago

Solve x2 - 8x + 14 = 2x - 7

BabaBlast [244]

Answer:

x=7, x=3

Step-by-step explanation:

$x^{2} -8x+14=2x-7$

$x^{2} -8x-2x+14+7=0$

$x^{2} -10x+21=0$

$\mathrm{For\:a\:quadratic\:equation\:of\:the\:form\:}ax^2+bx+c=0\mathrm{\:the\:solutions\:are\:}$

$x=$ $\frac{-b\pm \sqrt{b^2-4ac}}{2a}$

positive

$x=\frac{-\left(-10\right)+\sqrt{\left(-10\right)^2-4\cdot \:1\cdot \:21}}{2\cdot \:1}$

$x=7$

negative

$x=\frac{-\left(-10\right)-\sqrt{\left(-10\right)^2-4\cdot \:1\cdot \:21}}{2\cdot \:1}$

$x=3$

7 0

3 years ago

Suppose it takes 45 hours for robot A to construct a new robot. Working together with robot B, it takes 25 hours for both robots

Len [333]

Answer:

56 hours 25 minutes

Step-by-step explanation:

Given:

Suppose it takes 45 hours for robot A to construct a new robot

It takes 25 hours for both robots to construct a new robot.

Question asked:

How long would it take robot B to construct a new robot, working alone ?

Solution:

Let the time taken by robot B to construct new robot = $x$

By robot A

It takes 45 hours to construct = 1 new robot

It takes 1 hour to construct = $\frac{1}{45} \ new\ robot$

By robot B

It takes $x$ hours to construct = 1 new robot

It takes 1 hour to construct = $\frac{1}{x}$ new robot

By working together

It takes 25 hours to construct = 1 new robot

It takes 1 hour to construct = $\frac{1}{25} \ new\ robot$

$\frac{1}{25}$ new robot is constructed in = 1 hour

New robot is constructed by both working together in 1 hour = New robot is constructed by robot A in 1 hour + New robot is constructed by robot B in 1 hour

$\frac{1}{25} =\frac{1}{45} +\frac{1}{x} \\$

Subtracting both sides by $\frac{1}{45}$

$\frac{1}{25}-\frac{1}{45} =\frac{1}{45} -\frac{1}{45}+\frac{1}{x} \\\\\frac{1}{25}-\frac{1}{45} =\frac{1}{x}\\\\ Taking\ LCM \ of \ 25\ and\ 45,\ we\ got\ 225$

$\frac{9-5}{225} =\frac{1}{x} \\ \\ \frac{4}{225} =\frac{1}{x}\\\\ By\ cross \ multiplication\\4\times x=225\\Dividing\ both\ sides\ by\ 4\\x=56.25\ hours$