My brother has 55 science and technology books, and the number of science and technology books is 14 less than 3 times that of story books. How many story books does my brother have? I want them today! Equation, process

My brother has 55 science and technology books, and the number of science and technology books is 14 less than 3 times that of story books. How many story books does my brother have? I want them today! Equation, process

Let x storybooks 3x-14 = 553x = 14 + 553x = 69x = 69 / 3x = 23 storybooks

My brother has 55 science and technology books and some storybooks. The number of science and technology books is 14 times less than that of storybooks. How many storybooks does my brother have?

Suppose brother has x storybooks, 3x-14 = 55, & nbsp; & nbsp; 3x = 69, & nbsp; & nbsp; X = 23, answer: brother has 23 storybooks

My brother has 55 science and technology books and some story books. The number of science and technology books is 14 less than 3 times of story books. How many story books does my brother have

Suppose there are x storybooks
So the number of science and technology books is represented by Storybooks: 3x-14
In fact, there are 55 science and technology books
So, 3x-14 = 55
The solution is x = 23
There are 23 storybooks

How much resistance is needed to use LED as indicator light of 12V power supply?

The current of high brightness LED is 10ma-20ma. The working voltage of LED varies with different colors, generally between 2-3v, optional 2.5V. Series resistance = (12-2.5) / 10 = 1K Ω to (12-2.5) / 20 = 470 Ω

When x = what, is the quadratic polynomial of one variable X & # 178; + 2x twice the polynomial of one variable x + 2?

x²+2x=2(x+2)
x²+2x=2x+4
So x & # 178; = 4
x=±2

What is the difference between the power consumption of a 45 watt energy-saving lamp and a 45 watt ordinary bulb

But if it's only nominal, it should be 45W energy-saving lamp. The reading on the meter will be less. According to my practical experience, the difference should be about 5-10W. If you don't believe it, you can measure it with a power meter. The failure rate of energy-saving lamp is too high, so it's better to use Le lamp instead

Suppose the function FX is odd, F1 = 1 / 2, f [x + 2] = f [x] + F [2], then F5 is equal to

f(-1+2)=f(-1)+f(2)
f(1)=-f(1)+f(2)
1/2=-1/2+f(2)
f(2)=1
f(3)=f(1+2)=f(1)+f(2)=1/2+1=3/2
f(5)=f(3+2)=f(3)+f(2)=3/2+1=5/2

How many kilowatt hours of electric energy does a bulb marked with 220v100w consume when it is connected to a 220V circuit and works for 5 hours

1 degree = 1 kilowatt hour (KWH) = 3600000 joules (J)
W = Pt = 100W * 5h = 0.1kw * 5h = 0.5kwh, i.e. 0.5 kwh

Simple operation of 7-17 of 15-11 × 17 of 11

7 of 15-11-4 of 17 × 17 of 11
=15- 7/11 - 4/17 x 17/ 11
=15- 7/11 - 4/11
=15- ( 7/11 + 4/11 )
= 15 - 1
= 14

Forget about high school physics in college. How many joules is 1eV

1eV=1.60×10^-19 J