Dan is twice as old as Bob. The sum of their ages seven years ago was 13. How old are they now?

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`x`²	`x`^□	log_□	√☐	^□√☐	≤	≥	□□	·	÷	`x`^◦	π
(☐)^′	`ddx`	∂∂`x`	∫	∫_□^□	lim	∑	∞	`θ`	(`f` ◦ `g`)	`f`(`x`)

☐²

x^☐

√☐

^□√☐

□□

log_□

θ

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∫

ddx

≥	≤	·	÷	`x`^◦	(☐)	\|☐\|	(`f` ◦ `g`)	`f`(`x`)	ln	`e`^☐
(☐)^′	∂∂`x`	∫_□^□	lim	∑	sin	cos	tan	cot	csc	sec

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Steps Examples

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x+2y=2x−5, x−y=3

Solution

x=1, y=−2

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Solve by:

Solve by elimination

Solve by substitution

Solve by Cramer's rule

Solve by Gaussian elimination

One step at a time

[

x+2y=2x−5

x−y=3

]

Arrange equation variables for elimination

[

−x+2y=−5

x−y=3

]

Add the equations

x−y=3

−x+2y=−5

y=−2

[

−x+2y=−5

y=−2

]

For −x+2y=−5 plug in y=−2

Solve −x+2(−2)=−5 for x: x=1

The solutions to the system of equations are:

x=1, y=−2

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أهلاً, اطرح سؤالا حول x+2y=2x−5,x−y=3 أو اختر من الخيارات أدناه

حل بواسطة: substitution

حل بواسطة: Cramer's rule

حل بواسطة: Gaussian elimination

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−▭▭	<	7	8	9	÷	`AC`
+▭▭	>	4	5	6	×	☐☐☐
×▭▭	(	1	2	3	−	`x`
▭ \|▭	)	.	0	=	+	`y`

Dan is twice as old as Bob. The sum of their ages seven years ago was 13. How old are they now?

Solution

Solution steps

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