The diagonals of a square bisect one another and are perpendicular.
so 21x+ 16.5 = 90
subtract 16.5 from each side
21x = 73.5
divide by 21 on each side
21x/21 = 73.5 /21
x = 3.5
You should write numbers in as many ways as you possibly can to make new connections in your brain. Knowing how to write numbers in many different ways can help you solve complex problems more easily. Doing this can also reinforce the mathematical principles and logic you have memorised.
Writing one in many different ways:
1=1/1=2/2=3/3=4/4=(-1)/(-1)=(-2)/(-2)
=1.0=1.00=1.000=(1/2)+(1/2)=(1/3)+(1/3)+(1/3)
=(1/4)+(1/4)+(1/4)+(1/4)
Writing a half in many different ways:
1/2=(1/4)+(1/4)=(1/6)+(1/6)+(1/6)
=(1/8)+(1/8)+(1/8)+(1/8)=4*(1/8)
=2/4=3/6=4/8=5/10=0.5=0.50
etc...etc...
Answer:
4 x minus 5 y = negative 5 and 3 x + 10 y = negative 20
Step-by-step explanation:
The equations
4 x - 5 y = 5 (red)
3 x + 10 y = 20 (blue)
4 x - 5 y = -5 (green)
3 x + 10 y = -20 (purple)
are shown in the picture attached. As we can see there, the point (–2.7, –1.2) is on the intersection of the purple and green lines. Therefore is the solution of the system:
4 x - 5 y = -5
3 x + 10 y = -20
Ben's estimate gives 7 g of nickel; the actual amount is 8.03 g.
In 1 g of the substance, there is 0.52 g of copper and 0.25 g of zinc; this gives
0.52+0.25 = 0.77 g of the substance.
The remaining part of the substance is nickel:
1-0.77 = 0.23 g of nickel.
Using Ben's estimate, 0.2 g of nickel per gram of substance, we have
0.2(35) = 7 g of nickel in 35 g of the substance.
The actual amount is 0.23(35) = 8.03 g of nickel in 35 g of the substance.
