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16. Dacă 8a+3b/2b = 7/4, determinati a/b si B la puterea 2-a la puterea 2/15 ab ​

Răspuns :

Răspuns:

(8a + 3b) / 2b = 7/4

4(8a+3b) = 14b

32a + 12b =14b

32a = 14b - 12b

32a = 2b   /:2

16a = b

a/b = 1/16

a = b/16

b = 16a

(b² - a²) / 15ab =

(16²a²- b²/16²) / (15 × b/16 × 16a) =

[(16²)²a² - b²] /  16² / 15ab  =

[(16²)²a² - b²] /  [16² × 15ab]  =

(256a - b) ( 256a + b) / 3840ab

Răspuns:

[tex]\frac{8a+3b}{2b} =\frac{7}{4} \\\\4(8a+3b)=7*2b\\\\32a+12b=14b\\\\32a=14b-12b\\\\32a=2b= > \frac{a}{b} =\frac{2}{32} =\frac{1}{16} \\\\b=16a\\\\\frac{b^2-a^2}{15ab} =\frac{(b-a)(b+a)}{15a*16a} =\frac{(16a-a)(16a+a)}{240a^2} =\frac{15a*17a}{240a^2} =\frac{255a^2}{240a^2} =\frac{17}{16}[/tex]