56 - 8 (1/4+2 / 1-3/5)

Mathematics

1 answer:

saw5 [17]2 years ago

3 0

$56-8(\frac{\frac{1}{4}+2 }{1-\frac{3}{5} })= 56-8(\frac{2,25}{0,4 })= 56-8.(5,625)=56-45= 11$

ok done. Thank to me :>

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areas of four triangles are 40 cm^2, 90 cm^2, 202.5 cm^2 and 455.6 cm^2 are continue in sequence. the enlargement factor is 1.5,

maw [93]

Answer:

9th Triangle

Step-by-step explanation:

Given the area of four triangles: $40 cm^2, 90 cm^2, 202.5 cm^2 \:and\: 455.6 cm^2$

If the Scale factor is 1.5.

This is a geometric sequence and the common ratio is 1.5 X 1.5.

Therefore, the area of any n triangle can be determined using the function:

$A(n)=40\cdot1.5^{2(n-1)}$

We want to determine which triangle has an area greater than $15000cm^2$ .

When A(n)=15000

$40\cdot1.5^{2(n-1)}>15000\\1.5^{2(n-1)}>\frac{15000}{40} \\1.5^{2(n-1)}>375\\\text{Change to Logarithm form}\\2(n-1)>Log_{1.5}375\\\text{Applying logarithm change of base to base 10 law}\\2(n-1)>\frac{Log 375}{Log 1.5} \\2n-2>14.62\\2n>14.62+2=16.62\\n>8.31$