Question

Раскройте скобочки 15-(7a+(4a-(a-9))) Найдите не известное число x:5:4x=1:2

Answer 1

15-(7a+(4a-(a-9)))=15-(7a+(4a-a+9))=15-(7a+4a-a+9)=15-7a-4a+a-9=6-10а

x:5:4x=1:2
$\frac{x}{ \frac{5}{4x}}= \frac{1}{2} \\ {x}: \frac{5}{4x} =\frac{1}{2} \\ x* \frac{4x}{5}=\frac{1}{2} \\ \frac{4x^{2}}{5}=\frac{1}{2} \\ 8x^{2}=5 \\ x^2= \frac{5}{8} \\ x=+- \sqrt{ \frac{5}{8} } \\ x=+- \frac{ \sqrt{5}}{ \sqrt{8}} \\x=+- \frac{ \sqrt{5}}{ \sqrt{4*2}} \\ x=+- \frac{ \sqrt{5}}{2 \sqrt{2}} \\ x=+- \frac{ \sqrt{5}*2\sqrt{2}}{2\sqrt{2}*2\sqrt{2}} \\ x=+- \frac{ \sqrt{5*2}*2}{2*2\sqrt{4}} \\ x=+-\frac{2\sqrt{10}}{4*2}} \\ x=+-\frac{ \sqrt{10}}{4}$

Answer 2

15-(7a+(4a-(a-9))) First, let's simplify the expression inside the innermost parentheses: 15-(7a+(4a-a+9)) =15-(7a+(3a+9)) =15-(10a+9) Now, let's simplify the expression inside the parentheses: 15-10a-9 =6-10a So, the simplified expression is 6-10a.

Now, let's solve for the unknown number x in the equation 5/4x=1/2: To solve for x, we can cross multiply to get rid of the fractions: 5*2 = 4x*1 10 = 4x Now, divide both sides by 4 to solve for x: 10/4 = x 2.5 = x So, the unknown number x is 2.5.